212 SPECIAL BACTERIOLOGY 



(b.) NON-CHROMOGENIC. 



Micrococcus Radiatus. Small cocci with no typical arrangement. 

 On plate cultures the colonies appear surrounded by a radiating border. 

 In stab cultures the growth exhibits horizontal rays, and the gelatine is 

 liquefied slowly. 



III. VIBRIOS. 



Vibrio Aquatilis (Giinther). This vibrio is distinguished from 

 the cholera vibrio in the first few days of its development easily, and 

 with certainty by the character of its growth. It forms circular, smooth 

 edged, finely granular colonies. In later stages, when the gelatine 

 commences to liquefy, a faint resemblance to the colonies of the 

 cholera vibrio appears. The vibrio aquatilis is further distinguished 

 from the cholera vibro by the nitroso-indol reaction being negative, and 

 the total absence of any pathogenic properties. The vibro aquatilis at 

 first grew badly in fluid media, but after many generations, cultures 

 were obtained in bouillon and peptone water. Giinther failed to 

 observe the formation of spirilla with this vibrio. 



Vibrio Berolinensis. Found by Neisser in Berlin conduit water. 

 On gelatine plates the edges of the colonies are mostly smooth, and 

 exhibit a much more granular appearance than the colonies of the 

 cholera Asiatica vibrio ; the gelatine is liquefied slowly, and the nitroso- 

 indol reaction is positive. Guinea-pigs inoculated intraperitoneally, die 

 with the same symptoms as those following the introduction of the 

 genuine comma bacilli of Asiatic cholera. Similar vibrios have been 

 isolated by Weibel, Loffler, Fokker, Kiesling, and also from the river 

 Seine. 



The non-identity of this and the other vibrios with the real cause 

 of Asiatic cholera is determined by the negative results with Pfeiffer's 

 reaction and the agglutination test. 



Vibrio Metschnikoff. This vibrio was first found in an epidemic 

 amongst chickens, then in water from the river Spree. It is somewhat 

 thicker and shorter than the vibrio of Asiatic cholera, often exhibiting 

 a coccoid formation. It is stongly motile. The cultures resemble those of 

 the vibrio of Asiatic cholera, but the liquefaction of gelatine media is more 

 pronounced, and already in twenty-four hours there is a well-marked 

 nitroso-indol reaction present. This vibrio, in contradistinction to Koch's 

 vibrio, is just as pathogenic for pigeons as for guinea-pigs. (See Photo- 

 micrograph from blood of inoculated pigeon, Fig. 82.) 



Vibrio Gindha (Pasquale). Found in well water at Massauah ; 

 somewhat long, slightly bent rods, stongly motile, possessing one fla- 

 gellum. Slightly pathogenic ; nitroso-indol reaction negative. 



