450 MALIGNANT (EDEMA 



high powers of resistance, and may be kept for months in the 

 dried condition without being killed. As with other organisms, 

 it is probable that a number of bacilli exist which differ slightly 

 from the classical type. 



Experimental Inoculation. A considerable number of animals 

 the guinea-pig, rabbit, sheep, and goat, for example are 

 susceptible to inoculation with this organism. The ox is said 

 to be quite immune to experimental inoculation, though it can, 

 under certain conditions, contract the disease by natural channels. 

 The guinea-pig is the animal most convenient for experimental 

 inoculation. When the disease is set up in the guinea-pig by 

 subcutaneous inoculation with garden soil, death usually occurs 

 in about twenty-four to forty-eight hours. There is an intense 

 inflammatory oedema around the site of inoculation, which ex- 

 tends over the wall of the abdomen and thorax. The skin and 

 subcutaneous tissue are infiltrated with a reddish-brown fluid and 

 softened ; they contain bubbles of gas and are at places gangren- 

 ous. The superficial muscles are also involved. These parts 

 have a very putrid odour. The internal organs are congested, 

 the spleen soft but not much enlarged. 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 organ- 

 isms. 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 invariably 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 being softened and partly necrosed ; 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 con- 

 siderable 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 con- 

 siderably in different cases, and it always becomes diminished in 

 cultures grown for some time. A smaller dose produces a fatal 

 result when injected along with various other organisms (bacillus 

 prodigiosus, etc.). 



