80 BACTERIOLOGICAL EXAMINATION OF WATER. 



Spirillum Concentricum. 



Isolated by Kitasato from putrid blood, and found by Lustig 

 in water. It forms small screw-shaped forms ; in broth cultures 

 there may be from five to twenty spiral turns. It is very motile, 

 with a screw -like movement. It does not form spores. In 

 gelatine plates it forms circular discs, composed of concentric 

 rings ; the gelatine is not liquefied. In gelatine-stab it grows 

 chiefly on the surface, forming a cloud-like expansion. On agar 

 it forms a diffused growth, which adheres strongly to the medium. 

 On potato there is no growth. In broth there is a diffused 

 growth, and a slimy deposit appears at the bottom of the tube, 

 above which the broth is clear. 



The Spirillum volutans is found in stagnant water ; it forms 

 long threads with dark granular contents, each thread has 2J to 

 3J turns and has a long cilium at each end ; it is motile ; at 

 times, however, the threads appear quite motionless. The 

 Spirillum undula is found in stagnant water; it forms long 

 threads, which have 1J-3 turns; there is a bunch of cilia at each 

 end of the bacillus. 



The Spirillum serpens is very common in stagnant waters ; it 

 forms long threads with 3 or 4 turns ; at times the bacilli are 

 joined into long chains. It is very motile. 



The Spirillum tenue is found in stagnant water, and forms 

 long thin threads with 1J screw turns. It is very motile. 



