BACILLUS PERFRINGENS 517 



Toxins. A toxin is formed in broth culture to which 

 serum or fresh muscle has been added. The toxin is a 

 complex of a hsemolysin and another poisonous body. 

 The filtered toxin injected intravenously into a rabbit 

 produces great blood destruction. Injected subcu- 

 taneously into a guinea-pig, 2 c.c. causes oedema and 

 sloughing and death in three days. Rabbits can be 

 immunised with the toxin and yield an antitoxic serum 

 (Bull and Pritchett), and during the latter part of the 

 War an antitoxin serum was prepared in quantity by 

 injection of the toxin into horses. Butyric acid is freely 

 formed by the organism. 



Pathogenicity. The virulence of various strains of B. 

 perfringens varies, and the washed bacilli and their spores 

 are non-pathogenic. It is pathogenic for guinea-pigs and 

 mice, but much less so for rabbits. The whey of a milk 

 culture in quantities of 0-5-2 c.c. per 100 grm. of body- 

 weight produces death in a guinea-pig within forty-eight 

 hours, though spontaneous recovery from what should be 

 a lethal dose sometimes occurs. Post-mortem, if injected 

 subcutaiieously, the hair strips readily from the skin, 

 which may be green and gangrenous ; the subcutaneous 

 tissue may also be green and gangrenous, or more or less 

 digested, so that the skin hangs loose, and the sac formed 

 contains gas and exudation, sometimes scanty, sometimes 

 abundant, thin and sanguinolent, and containing numbers 

 of bacilli ; the blood-stream is invaded relatively early 

 in the course of the infection. Around the gangrenous 

 area the tissues are markedly oedematous. If the post- 

 mortem be delayed, or if the heart-blood be taken up into 

 tubes, and these are sealed and incubated for some hours, 

 many of the bacilli will spore. Pigeons, by intra-muscular 

 inoculation, are also susceptible. Injected intravenously 

 into a rabbit, the animal killed immediately and the 

 carcase incubated at 37 C. for twenty-four hours and 



