ANTHRAX GROUP 



335 



fatally. Pulmonary infection resulting in a pneumonia with 

 quickly fatal termination may occur from inhalation. 



Immunity. No true toxin has been demonstrated for the 

 anthrax bacillus, in fact, it is difficult to account for the patho- 

 genicity of the organism on the basis of specific poison formation. 

 Immune serum is claimed by some investigators to have a con- 

 siderable specific agglutinative power, but others have failed to 

 demonstrate this. It seems that this reaction is inconstant and 

 may be entirely absent, even though the serum have a high im- 

 munizing value. Certain normal bloods, as from the dog, show 

 bacteriolytic power, but specific bacteriolysins cannot be demon- 

 strated in most immune sera. Opsonins, both normal and im- 



Fig. 139. Bacillus anthracis, stained mount of blood, showing the capsules of 

 the bacilli (Preisz). 



mune, have been demonstrated. Aggressins, according to Bail, 

 account for its pathogenicity. Many theories of immunity in 

 anthrax have been developed, but none of fhem has been gener- 

 ally accepted as solving the problem wholly. 



Active immunization by vaccination has been extensively 

 practised. The organism may be attenuated in a variety of ways. 

 The first developed was that of Pasteur, and it is still the one most 

 commonly used. The organism is grown at a temperature of 

 42 to 43 for varying lengths of time. The pathogenicity grad- 

 ually decreases until injections no longer kill the rabbit; longer 

 growth attenuates it until the guinea-pig is not susceptible, and 

 finally even the mouse will not succumb. The exact length of 

 time required for attenuation in each instance can be determined 



