408 MICRO-ORGANISMS IN WATER 



SPIRILLUM CONCENTRICUM 



Authority. Kitasato, ' Ueber die Reincultur ernes Spirillum aus faulendem 

 Blute,' Centralblatt f. Bakteriologic, vol. iii., 1888, p. 73. 



"Where Found. In putrid blood. Included by Lustig (loc. cit.) amongst 

 organisms found in water. 



Microscopic Appearance. Small screw-shaped forms with 2 to 3 twists, 

 and with pointed ends. In broth cultures they form long screws with 5 to 20 

 twists. The diameter of the screw is 2'0 to 2-5 /j., and the length of one twist 

 3'5 to 4 /*. In thickness it slightly exceeds the Comma spirillum. It is very 

 motile, with a screw-like movement. No spore formation observed. 



Cultures. 



GELATINE PLATES. Appears in transmitted light as pale grey circular disc 

 composed of concentric cocade-like rings. The centre is whitish and opaque ; 

 then follows a transparent ring, then an opaque grey white circle double as 

 broad, then a very narrow transparent ring, and finally a broadish greyish white 

 band, from which are seen extending (under a low power) numerous small twisted 

 prolongations. No liquefaction takes place. 



GELATINE TUBES. It grows more on the surface than in the depth, and 

 after several weeks the whole surface of the gelatine is covered with a cloud- 

 like expansion. 



AGAK-AGAB. Forms a diffused expansion over the surface which adheres so 

 firmly to the agar-agar that it is almost impossible to get any of the growth 

 without bits of agar. 



POTATOES. It does not grow either at the ordinary temperature or at 37 C. 



BBOTH. Benders it slowly turbid. In very old cultures an abundant slimy 

 deposit collects, whilst the liquid remains clear. 



Kemarks. Not pathogenic to mice, guinea-pigs, or rabbits. 



SPIRILLUM VOLUTANS (Ehrenberg) 



Where Found. In stagnant water and especially in marsh- water. (Lustig, 

 loc. cit.) 



Microscopic Appearance. Filaments 25 to 30 p. long and from 1-5 to 2 yu 

 broad, the ends slightly thinner and rounded, having 2 to 4 spiral turns wide 

 apart. Each filament has a cilium. In the interior of the protoplasm numer- 

 ous dark granulations are visible, considered by some observers to be sulphur. 

 It is very motile, although according to Lustig the filaments are sometimes 

 motionless. 



SPIRILLUM LEUCOMELAENUM 



Authority.- Perty, Zur Kenntniss Jdcinster Lebensformcn. Berne, 1852. 



Where Found. In stagnant water. 



Microscopic Appearance. Short individuals joined on end to end and 

 forming spirilla with 2 to 3 spiral turns. The contents are deep black, sur- 

 rounded by a clear aureole. 



