NATURAL KACES OF BACTERIA 123 



to distinguish with certainty a preparation of the Vibrio metch- 

 nikovi from one of Koch's cholera spirillum, and the differences 

 in the mode of growth of the two are not greater than may be 

 determined between two cultures of the cholera spirillum of 

 different origin. Yet Vibrio metchnikovi is pathogenic for 

 pigeons and fowls and only affects guinea-pigs (which are sus- 

 ceptible to inoculations of the cholera spirillum) when inoculated 

 in relatively large quantities. According to Gamaleia 1 injec- 

 tions of the Vibrio metchnikovi render guinea-pigs immune 

 to cholera. Pfeiffer denies this, though Gamaleia has reiterated 

 the statement, 2 and ascribes Pfeiffer's failure to gain immunity 

 to the fact that he employed attenuated cultures. It must, 

 however, be admitted that Gamaleia's statement still awaits 

 confirmation, and, for the present, it is better to look upon the 

 series of microbes which includes Koch's spirillum of Asiatic 

 cholera, the Finkler-Prior spirillum of Cholera nostras, Deneke's 

 S. tyrogenum, Miller's spirillum obtained from the mouth, and 

 the Vibrio metchnikovi as a group of very closely allied species. 



Similarly so high an authority as Professor Hueppe 3 would 

 class together into one group, as the bacteria of haemorrhagic 

 septicaemia, a large number of bacteria which microscopically 

 are indistinguishable, whose ends stain more deeply than the 

 central region, whose growth upon bacteriological media is 

 similar, and which, further, are identical in the appearance of 

 the individual colonies. C. Frankel 4 would separate these into 

 two groups, one including the bacillus of ferret plague (Eberth 

 and Schimmelbusch), the bacillus of swine plague (Billings), 

 that of hog cholera (Salmon), that of Danish swine plague 

 (Selander), and the bacillus of the German " Schweinepest." 

 All these are motile and ciliated. The other group contains 

 forms that are identical, or almost identical, namely, Loffler's 

 bacillus of chicken cholera, Schutz's swine plague bacillus, 

 Cornil's bacillus of duck cholera, Gaffky's microbe of rabbit 

 septicaemia, and Kitt and Hueppe's bacterium of " Wildseuche ' 

 (deer plague). All these only differ in regard to the animals 

 which they specially affect. 



Here, too, I would mention a most interesting observation of 



1 Gamaleia, Annates de VInst. Pasteur, iii., 1889, p. 609. 



2 Ibid, iv., 1890, p. 330. 



3 Hueppe, Berliner Iclin. Wochenschrift, No. 9, 1890. 



4 C. Frankel, Grundriss der Bahterienkunde, Berlin, 1891, p. 401. 



