400 MICRO-ORGANISMS IN WATER 



V I.BR10 BK HOL ENENSIS 



LIQUEFIES GELATINE 



Authority. Neisser, ' Ueber einen neuen Wasser- Vibrio, cler die Nitrosoindol- 

 reaction liefert,' Archivf. Hygiene, 1893, p. 194. 



Where Found. In filtered river Spree water. 



Microscopic Appearance. Usually somewhat smaller than the cholera 

 bacillus ; otherwise undistinguishable. Very motile ; one long and much twisted 

 cilium is attached to one end of the rod. No spore formation observed. Is 

 discoloured by Gram's method. 



Cultures. 



GELATINE PLATES. Liquefies the gelatine much more slowly than the cholera 

 bacillus ; is often hardly visible on the plate, even after forty- eight hours. Under 

 the microscope at the end of twenty-four hours the depth colonies are small, 

 circular and smooth-rimmed, the contents are very slightly and finely granulated, 

 they are colourless and transparent. The surface colonies form small trans- 

 parent skin-like expansions, with a central circular disc. No depression is formed 

 in the gelatine, and the edge of the colony always remains sharply denned. 



GELATINE TUBES. In gelatine tubes it is only distinguished from the 

 cholera bacillus by its markedly slower growth. 



AGAB-AGAR AND GLYCERINE-AGAE. Kesembles the cholera bacillus. 



POTATOES. On ordinary potatoes, as well as 011 those treated with soda, 

 vinegar, and salt respectively, it resembles the cholera bacillus. 



BROTH. Benders strongly alkaline broth more rapidly and decidedly turbid 

 at 20 to 22 C. and at 37 C. than the cholera bacillus ; otherwise resembles the 

 latter. Grows very luxuriantly and much more so than the cholera bacillus in 

 pancreas broth. 



STERILE WATER. At 37 C., after six days no visible growth, but when 

 sterile 1 per cent, pepton-water was added to these tubes, turbidity began 

 forty-eight hours later ; the cholera bacillus tube, however, remained clear, no 

 growth having taken place. 



STERILE MILK. No coagulation, and forms no acid ; therefore resembles the 

 cholera bacillus. 



Remarks. It will not grow at 10 3 C., and is destroyed when kept at 60 C. for 

 five minutes. Gives the ' cholera-red ' or iiitrosoindol reaction. Is pathogenic to 

 guinea-pigs, but not to mice, rabbits, or pigeons. 



Note. Sanarelli (' Les Vibrions des Eaux et 1'Etiologie du Cholera,' Annales de 

 I'lnstitut Pasteur, vol. vii., 1893, p. 693) isolated no less than thirty-two different 

 vibrios from the river Seine, drain-water, sewage-effluent, and pond- water, four of which 

 gave the ' cholera-red ' or iiitrosoindol reaction and were pathogenic to guinea-pigs. 

 Sanarelli is of opinion that there may be numerous vibrios capable of exciting cholera, 

 and that the idea of its propagation being due to one particular variety is untenable. 

 (See pp. 279 and 283.) 



