338 MICROBIOLOGY 



obtained from the macerated tissues of the stomachs of pigs. 

 The toxin contained in filtrates of such cultures is quite re- 

 sistant to heat. Hanna 3 studied the toxins of B. Chauveaui 

 produced by the organism. He found that a culture medium 

 consisting of blood plasma and peptone broth in the proportion 

 of 1 to 5 gave the best toxins and that this toxin became at- 

 tenuated. He observes that guinea pigs which had received 

 the toxin appeared to be less sensitive to the toxin than fresh 

 animals. He procured an antitoxin from the blood of rabbits 

 that had received repeated doses of the toxins. 



Pathogenesis. The bacillus of symptomatic anthrax is 

 pathogenic for cattle six months of age or older, but rarely 

 after they are six years old. It does not usually attack cattle 

 under six months of age. Swine, horses, rabbits, dogs, cats 

 and chickens are as a rule immune. The guinea pig is the 

 most susceptible of the experimental animals. The lesions in 

 the guinea pig consist of a blood stained serous exudate in the 

 subcutaneous tissues extending from the point of inoculation 

 over a considerable part of the abdomen. Naturally it is a 

 disease of cattle, sheep and horses. Man has not been infected. 



Resistance. Norgaard states that a temperature of 

 110 C. is necessary to destroy the dried spores. A 2 per 

 cent solution of carbolic acid kills the vegetative forms after 

 some hours. For disinfection purposes a 5 per cent carbolic 

 acid solution or a 1 to 2000 corrosive sublimate solution is 

 recommended. 



Immunity. An active immunity against the bacillus of 

 black leg is obtained by subcutaneously inoculating cattle with 

 tissue extracts from infected animals. Several forms of vac- 

 cine have been prepared. The earlier ones required two 

 vaccines. At present, however, the U. S. Bureau of Animal 

 Industry prepares a single vaccine. The material used for 

 the vaccine is obtained from a fresh blackleg tumor, by pound- 

 ing the muscle tissue in a mortar with the addition of a little 

 water and squeezing the pulp through a linen cloth. The 



Hanna. Jour, of Path, and Bact., Vol. IV (1896) p. 383. 



