BACILLUS AEROGENES CAPSULATUS 471 



Subcutaneous inoculation of pure culture into a susceptible subject 

 produces, within twenty-four to thirty-six hours, an acute edematous 

 inflammation about the point of inoculation. The edema extends 

 throughout the subcuticular and deeper layers, and consists of thin, 

 shghtly bloody fluid. Neighboring lymph nodes become swollen and 

 hemorrhagic. In the mixed infections of accidental inoculation, but 

 more rapidly in experimental inoculations with pure cultures, gas is 

 formed and consequent subcutaneous emphysema. Together with this 

 there are symptoms of general toxemia. In the smaller test animals this 

 disease is usually fatal. At autopsy the bacilli are found in the edema 

 fluid about the local lesion. At autopsies done soon after death, the 

 organisms are not found in the blood or internal organs. Later thej-^ 

 may be generally distributed throughout the body. In mice only may 

 the bacilli enter the blood stream before death. The internal organs 

 of animals dead of this infection usually show parenchymatous degen- 

 eration and occasionally hemorrhages. 



Malignant edema is not a frequent disease. It has been occasionally 

 observed in horses, in cattle, and in sheep. In man the infection usually 

 appears after traumatism or secondarily after compound fractures or 

 upon the site of suppurating wounds. Isolated cases have been de- 

 scribed as arising after hypodermic injections. One case has been 

 reported as arising in the uterus after instrumental abortion. 



Immunity. — Recovery from an infection with the bacillus of malig- 

 nant edema produces immunity against subsequent infections.^ The 

 bacillus in fluid media produces small amounts of a soluble toxin which 

 in bacteria-free filtrates is capable of killing guinea-pigs. Relatively 

 large quantities of filtrate must be employed. Roux and Chamberland,^ 

 the first to work upon these toxins, were able, by means of them, to 

 immunize guinea-pigs. Similar immunity could be produced by treat- 

 ment with the toxic, filtered sera of animals dead of the disease.^ 



BACILLUS AEROGENES CAPSULATUS 



Bacillus aerogenes capsulatus was first observed by Welch and fully 

 described by Welch and Nuttall * in 1892. It is identical with a bacillus 



' Arloing et Chauveau, Ann. de m^d. v6t., 1884. 



'' Boux et Chamberland, Ann. de I'inst. Pasteur, 1887. 



'Sanfelice, Zeit. f. Hyg., xiv. 



» Welch and Nuttall, Bull. Johns Hopkins Hosp., iii, 1892, p. 81. 



