QUALITATIVE BACTERIOLOGICAL ANALYSIS. 149 



Broth Cultures. Uniform turbidity occurs in twenty-four 

 hours at 20 C., and a very faint scum forms on the surface. 



Litmus-milk Cultures. No clotting or production of acidity. 



Indol. No indol is formed even after twenty days at 20 C. ! 



Microscopical Appearances. In most cultures it appears as a 

 large micrococcus. In the spreading edge of the colony the 

 elements are distinctly longer than broad ; nearer the centre 

 they are oval, and frequently united in pairs ; at or about the 

 centre they are perfectly spherical. 



Remarks. This microbe has been called B. subtilissimus on 

 account of the thin, almost gauze-like, character of the surface 

 colonies in gelatine-plate cultures. 



Bacillus Membraneus Patulus. 



Isolated from crude sewage and effluent from coke-beds. 



Gelatine Plates. The surface colonies appear as coarsely 

 granular, greyish-white films of somewhat irregular shape. 

 From the spreading edge of the colony processes extend in a 

 tortuous fashion over the surface of the medium, often forming 

 patterns of great delicacy and beauty. Beneath the surface 

 film-like growth slow liquefaction of the gelatine occurs. 

 Under a low power the colonies present a characteristic, 

 granular, and striated appearance. 



Gelatine-streak. In less than two days at 20 C. a coarsely 

 granular film forms on the surface of the gelatine, which spreads 

 rather rapidly ; from the margin processes are given off' which 

 wind over the gelatine in a characteristic way. Soon a longi- 

 tudinal pitting of the bacterial film along the line of inocu- 

 lation is observed, and the growth sinks down to the foot of the 

 tube. 



Agar-streak. In one night at 37 C. the growth appears as 

 a coarse, granular, semi-transparent, greyish-white film. In old 

 cultures the surface assumes a tuberculated appearance. 



Gelatine-stab. The growth varies ; sometimes there is lique- 

 faction down the line of the stab with tuft-like processes 

 extending into the solid medium, and at other times there is no 

 liquefaction, and the processes extend to the wall of the tube. 

 The growth on the surface is like a surface colony in a gelatine 

 plate. 



