356 AGEICULTUEAL AND INDUSTEIAL BACTEEIOLOGY 



follows. Radical intervention and the removal of tlie car- 

 buncle is usually carried out. 



In animals which have died of anthrax there is usually 

 to be noted a considerable enlargement of the spleen and a 

 decided softening of its pulp. Usually there are also hemor- 

 rhages and hemorrhagic exudates. Hemorrhages usually 

 appear in the liver and lungs. 



Immunity. — As previously noted immunization against 

 anthrax was first developed by Pasteur. This investigator 

 found that when the organism was grown in pure culture at 

 temperature decidedly above the optimum, usually from 42° 

 to 43° c. for varying lengths of time, the ability to produce 

 disease gradually diminished. Cultures could be finally 

 secured which when injected into rabbits would no longer 

 kill them, but which were sufficiently virulent to kill guinea 

 pigs and mice. Still longer cultivation at this high tem- 

 perature will attenuate or weaken the organism still more, 

 until guinea pigs are only occasionally killed by injection. 

 Vaccination in sheep and cattle is most commonly per- 

 formed by the injection of a highly attenuated culture; 

 after the subsidence of all reaction, a culture somewhat less 

 attenuated is injected as the second vaccine. As a result 

 of the methods introduced by Pasteur, the disease anthrax 

 has ceased to be a serious menace to the live stock industry 

 of France and other European countries. 



It is possible to secure an active antiserum by the hyper- 

 immunization of animals by the injection of attenuated, 

 then of more and more virulent cultures. 



Transmission. — ^Anthrax is usually transmitted from 

 animal to animal with feed, more rarely through lesions in 

 the skin. Infection by inhalation and through the skin are 

 most common in man. Animals which have died of anthrax 

 should be completely destroyed by burning or by deep bury- 

 ing. This organism is peculiar in that it does not form 

 spores within the body away from the air, but spores may 



