454 MICRO-ORGANISMS IX WATER 



BACILLUS GEANULOSUS 



I LIQUEFIES GELATINE | 



Authority. — Eussell, ' Untersuchungen iiber im Golf von Neapel lebende 

 Bacterien,' Zeiischrift fur Hygiene, vol. xi., 1891, p. 194. 



Where Found.— Obtained very frequently in sea mud near the coast, and' 

 also at a depth of 1,100 metres, where it was more abundant than any other 

 form. 



Microscopic Appearance. —In suspended gelatine drop-cultures this bacillus 

 forms long, slender threads, the individuals composing which are rather large 

 bacilli, with thick membrane and finely granular protoplasmic contents. In 

 older cultures the threads break up into short irregular pieces, and the isolated 

 bacilli are shorter, plump, and coarsely granular. It forms spores enclosed in 

 short fat cells, which are often much broader than long. In broth cultures at 

 37° C. a slow swinging movement is apparent, but usually it is not motile. It 

 is coloured by Gram's method, and will stain easily with fuchsin, Ziehl's 

 solution, whilst with Eiihne's carbolic methylene blue (see p. 46) the granular 

 particles are more strongly coloured than the other portions of the cell. 



Cultures.— 



Gelatine Plate s.^ — The surface colonies are usually thin, almost transparent^ 

 and spread out like a leaf. Under a low power the edge is smooth and irregular ; 

 concentric lines are visible, due to the parallel arrangement of the filaments ; 

 the surface is furrowed, which produces irregular light or dark lines recalling 

 the veins in a leaf. Liquefaction soon commences, and the periphery becomes 

 irregular and prolongations from the central mass- of the colony penetrate into 

 the surrounding gelatine. In the depth the colonies are small, round, shining 

 and opaque. The contents of the colonies are stringy, and often a whole surface 

 colony comes away on the point of the needle. 



Gelatine Tubes. — Forms a flat liquid depression, at the bottom of which 

 the growth collects. Later the lower layers of gelatine also become fluid. 



Agak-agar. — Forms after two or three days, or at 37° C. after twenty-four 

 hours, a sparse thin growth consisting of yellowish or whitish spots. Near the 

 condensed water, where the agar is moister, it grows more abundantly, pro- 

 ducing an intensely white expansion. 



Potatoes. — Forms a thick shining white and stringy ijatch, which later 

 becomes dull and wax-like, and becomes gradually more and more brown. 



Broth. — Renders it turbid, and produces a considerable deposit. 



Bemarks. — Although ain-obic, it will grow anaerobically, but no considerable 

 growth takes place. 



