252 PATHOGENIC BACTERIA. 



act in a manner resembling the pulverized spinal cords 

 of the rabbits used in rabies, and give an almost per- 

 fect immunity. Roux and Chamberland have found that 

 filtered cultures can also produce immunity when properly 

 introduced into animals. 



The immunity to symptomatic anthrax seems, how- 

 ever, to be one of degree, for Arloing, Cornevin, and 

 Thomas found that when the bacillus was introduced 

 into the animal body simultaneously with a 20 per cent. 

 solution of lactic acid, either the virulence of the bacil- 

 lus or the resistance of the tissues was so changed that 

 natural immunity was destroyed and the bacteria allowed 

 to develop and produce the disease. Roger found also 

 that refractory animals, like the rabbit, mouse, pigeon, 

 and chicken, could be made susceptible by the combined 

 injection of the Rauschbrand bouillon, the Bacillus pro- 

 digiosus, Proteus vulgaris, and other harmless organisms. 



When the guinea-pig is inoculated with the bacillus of 

 symptomatic anthrax, it dies in from twenty-four to 

 thirty-six hours. The post-mortem examination shows 

 a bloody serum at the point of inoculation, and the mus- 

 cles are dark red or black, like those of the ' ' black-leg ' ' 

 of cattle. No changes are apparent in the internal organs. 

 The bacilli are at first found near the point of inocula- 

 tion in the inflammatory exudations only, but soon after 

 death, being motile, they spread to all parts of the body. 



The peculiarities of symptomatic anthrax point to the 

 entrance of the bacteria into the animal body through 

 wounds, but the occurrence of epidemics at certain geo- 

 graphical points, known technically as * ' Rauschbrand 

 stations," suggests that infection may also take place 

 through the respiratory and alimentary tracts. 



At first thought, as Frankel points out, one might 

 imagine that an animal dead of quarter-evil and the dis- 

 charges from its body might be harmless, as compared, 

 for example, with the cadavers and discharges of anthrax, 

 because of the purely anaerobic method of the growth of 

 the bacillus of symptomatic anthrax and the rapidity of its 



