392 MALIGNANT (EDEMA 



liquefaction occurs around the colonies, and spheres with turbid 

 contents result ; gas is developed around the colonies. 



In deep tubes of glucose agar at 37 C., growth is extremely 

 rapid. Along the line of puncture, growth appears as a some- 

 what broad white line with short lateral projections here and 

 there (Fig. 131, B). Here also gas may be formed, but this is 

 most marked in a shake culture, in which the medium becomes 

 cracked in various directions, and may be pushed upwards so 

 high as to displace the cotton-wool plug. The cultures possess 

 a peculiar heavy, though not putrid, odour. 



Spore formation occurs above 20 C., and is usually well 

 seen within forty-eight hours at 37 C. The spores have the 

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

 the dried condition without being killed. 



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 

 extends 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 

 gangrenous. The superficial muscles are also involved. These 

 parts have a very putrid odour. The internal organs are con- 

 gested, the spleen soft but not much enlarged. In such con- 

 ditions 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 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. 



