CHAPTER XXI. 



BACTERIACE^E: THE BACTERIA OF THE HEMOR- 

 RHAGIC SEPTICEMIAS, PLAGUE AND MALTA FEVER. 



Bacillus (Bacterium) Avisepticus. Moritz 1 in 1869 observed 

 this minute rod in the blood of chickens with chicken cholera. 

 Toussaint (1879) and Pasteur (1880) obtained pure cultures in 

 liquid media and Pasteur (1880) made the far-reaching discovery of 

 the method of immunization by means of attenuated bacterial 

 cultures while working with this organism. B. avisepticus occurs in 

 enormous numbers in the blood, internal organs, urine and feces of 

 the acutely affected birds, in far smaller numbers in those having 

 the chronic form of the disease and has also been found in the in- 

 testinal contents of apparently healthy birds. It is 0.3^ wide and 

 0.2 to iju in length, the shorter ones being joined together. 

 It is non-motile and Gram-negative. Cultures are readily ob- 

 tained on ordinary media by inoculation with heart's blood. 

 Gelatin is not liquefied. Minute quantities of a virulent culture 

 suffice to produce a fatal infection in chickens and many other 

 birds, either by feeding or by subcutaneous injection. Rabbits 

 are also extremely susceptible, guinea-pigs almost immune. 

 Artificial cultures kept for three to ten months in contact with air 

 are no longer capable of causing a fatal infection in chickens and 

 their injection is followed by recovery and a state of immunity to 

 the fully virulent organism. Acute chicken cholera is the typical 

 hemorrhagic septicemia of birds, with abundant bacteria in the 

 blood, and hemorrhages on the serous membranes and into the 

 stomach and intestine. 



Bacillus (Bacterium) Plurisepticus. This name is applied to 

 an organism occurring in the hemorrhagic septicemias of various 



1 Vallery-Radot: Life of Pasteur, 1911, Vol. II, p. 75. 



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