PASTEURELLA 481 



rows, wild and domestic ducks, are also susceptible to the disease, 

 and rabbits and guinea-pigs can be successfully inoculated ; in 

 the latter animal a local abscess sometimes forms instead of a 

 general infection. By continuous cultivation with free access of 

 oxygen the virus becomes attenuated, and Pasteur was able thus 

 to prepare a vaccine which protected fowls. 



The bacillus of chicken cholera belongs to the group of hcemor- 

 rhagic septiccemic bacilli known to the French under the generic 

 name of Pasteur ella, and may be identical with Koch's bacillus of 

 rabbit septica3mia. The bacillus of swine plague, B. suisepticus 

 [P. suiseptica], also belongs to this group. This is 'a disease of 

 swine now regarded as being a form of swine fever, and the bacillus 

 as a secondary or terminal infectant. These organisms tend to 

 form a stalactite growth in butter broth. 



Mouse Septicaemia 



This disease may be conveniently described here. Koch first 

 obtained a minute bacillus (B. murisepticus) by injecting putre- 

 fying material subcutaneously into mice, the organism being met 

 with in large numbers in the blood and tissues. It seems to be 

 identical with the bacillus found in swine erysipelas (B. [Erysipe- 

 lotJirix] erysipelatos-suis), measures only 1 p in length, and occurs 

 in considerable numbers in the leucocytes. The bacillus stains 

 well by Gram's method, and is stated by some writers to be motile. 

 It grows readily, forming on agar extremely delicate, almost 

 invisible colonies ; in stab gelatin cultures after some time a 

 delicate cloudiness radiates from the central puncture. From an 

 agar culture the bacilli are somewhat larger than those found in 

 the animal body, and form filaments. It is pathogenic for swine, 

 rabbits, and mice. 



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