ANTHRAX 139 



pleurisy. The virulence of this organism becomes attenuated 

 when : 



{a) Cultivated in the blood of a non-susceptible animal. 



(b) When cultures are allowed to remain some months before 

 subcultures are made. 



(c) After the organism has been subcultured a considerable 

 number of times. 



(d) When exposed to sunlight. 



Cultures which are so attenuated that their injection into 

 guinea-pigs is not fatal, may have their virulence restored 

 by passing two or three times through young mice. 



Immunity, which, however, according to Petermann, is 

 transitory, seldom lasting more than a few months, may be 

 conferred upon susceptible animals by successive injections 

 into their blood of either — 



(a) Attenuated cultures ; 



(b) Filtered cultures (bacillifree) ; or 



(c) The blood serum of immunised animals. 



When protected animals are inoculated with a virulent 

 culture, the bacilli do not enter the circulation, and only 

 local suppuration occurs. 



Practical Disinfection. — Any animal dead of anthrax must 

 be buried deep in the ground, and then the putrefactive 

 organisms will kill the anthrax bacilli, and no spores will 

 be found. Discharges from an infected animal are highly 

 dangerous to man and other animals, so that stables 

 polluted with infective discharges should be washed out 

 with a strong solution of bleaching-powder (8 ounces to 

 the gallon), and harness, if possible, disinfected. It is 

 best and safest to destroy the carcase by burning in a 

 ' destructor.' 



