630 NON-PATHOGENIC BACILLI. 



growth occurs along the line of inoculation, which has a slightly yellowish 

 color; liquefaction commences after some weeks. Upon the surface of 

 agar an abundant, glistening layer of a gamboge-yellow color. Upon 

 potato development occurs slowly along the impfstrich; the growth has 

 at first an india-yellow color, which later becomes ochre yellow. 



264. BACILLUS HELVOLUS (Zimmermann). 



Found in the Chemnitz water supply. 



Morphology. Bacilli from 1.5 to 4.5 // in length and about 0.5 n broad; 

 usually in pairs, but also in chains of four or more elements and in long 

 filaments. 



Biological Characters. An aerobic, liquefying, motile (rotary motion 

 only), chromogenic bacillus. Forms a Naples-yellow pigment. Spore for- 

 mation not observed. Grows rather rapidly at the room temperature. Upon 

 gelatin plates the deep colonies are small, spherical, and of a pale-yellow 

 color ; when they come to the surface they form a prominent pale-yellow 

 drop, which lies in a shallow cavity. The superficial colonies for some time 

 have a sharply defined contour and an irregular outline ; by transmitted 

 light they have a dark-brown color. In gelatin stick cultures a button-like 

 mass of a Naples-yellow color forms about the point of puncture ; this gradu- 

 ally extends until it nearly reaches the walls of the test tube ; in the n.ean- 

 time the gelatin below is slowly liquefied and a saucer-shaped depression is 

 formed ; liquefaction progresses very slowly. Upon the surface of agar 

 an abundant layer of a Naples-yellow color is developed. Upon potato a 

 tolerably thick and abundant, shining, yellow layer, which frequently has 

 a shade of green. 



265. BACILLUS OCHRACEUS (Zimmermann). 



Found in the Chemnitz water supply. 



Morphology. Bacilli with round ends, from 1.25 to 4.5 /* long and from 

 0.65 to 0.75 /f broad; usually in pairs, or in chains containing several ele- 

 ments, also in long jointed filaments. In stained preparations a capsule-like 

 envelope may often be seen. 



Biological Characters. An aerobic, liquefying, motile, chromogenic 

 bacillus. Forms an ochre- yellow pigment. Spore formation not observed. 

 Motions slow and serpentine. Grows rather slowly best at the room tem- 

 perature. Upon gelatin palates forms small, pale-yellow, spherical colonies, 

 which gradually increase in size and cause the gelatin above them to become 

 liquefied, so that they lie at the bottom of a saucer-shaped cavity ; here the 

 color is more intense and becomes a golden ochrous yellow ; later the yel- 

 low mass extends in diameter, and is of a paler yellow color at the mar- 

 gin than at the centre. Under a low power the colonies are seen at first as 

 granular, yellowish-brown discs ; later they are covered with wart-like pro- 

 jections. ID gelatin stick cultures liquefaction occurs at first in funnel 

 form, and when it extends to the walls of the tube it gradually progresses 

 downward ; a pale-yellow deposit is seen at the bottom of the liquefied gela- 

 tin, which later acquires an ochrous-yellow tint. Upon the surface of agar 

 an ochrous-yellow layer is formed, which at the end of four to six weeks 

 has a breadth of about six millimetres at the lower portion of the impfstrich. 

 Upon potato a thin, ochrous-yellow layer is developed. 



266. BACILLUS PLICATUS (Zimmermann). 



Found in the Chemnitz water supply. 



Morphology. Small, thin bacilli with rounded ends, about 0.48/* (?) in 

 length and 0.45 /* broad; usually in pairs, but also in chains of four or more 

 elements. 



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

 genic bacillus. Forms a grayish-yellow pigment. Spore formation on 



