372 MALIGNAAT (EDEMA. 



organs are congested, the spleen soft but not much en- 

 larged. In such conditions the bacillus of malignant 

 oedema, both in short and long forms, will be found in the 

 affected tissues along with various other organisms. Spores 

 may be present, especially when the examination is made 

 some time after the death of the animal. If the animal 

 is examined immediately after death, a few of the bacilli 

 may be present in the peritoneum and pleurae, usually in 

 the form of long motile filaments, but they are almost in- 

 variably absent from the blood. A short time after death, 

 however, they spread directly into the blood and various 

 organs, and may then be found in considerable numbers. 



Subcutaneous inoculation with pure cultures of the 

 bacillus of malignant oedema produces chiefly a spreading 

 bloody oedema, the muscles presenting a bright-red colour ; 

 but there is little formation of gas, and the putrid odour is 

 almost absent. 



When the bacilli are injected into mice, however, they 

 enter and multiply in the blood stream, and they are found 

 in considerable numbers in the various organs, so that a 

 condition not unlike that of anthrax is found. The spleen 

 also is much swollen. 



The virulence of the bacillus of malignant oedema 

 varies considerably in different cases, and it always be- 

 comes diminished in cultures grown for some time. To 

 produce a fatal disease, a relatively large number of the 

 organisms is necessary, and these must be introduced 

 deeply into the tissues, inoculation by scarification being 

 followed by no result. A smaller dose produces a fatal 

 result when injected along with various other organisms 

 (bacillus prodigiosus, etc.). 



Immunity. Malignant oedema was one of the first 

 diseases against which immunity was produced by injec- 

 tion of toxines. The filtered cultures of the bacillus in 

 sufficient doses produce death with the same symptoms 

 as those caused by the living organisms, but a relatively 

 large quantity is necessary. Chamberland and Roux 

 (1887) found that if guinea-pigs were injected with several 



