520 A MANUAL OF BACTERIOLOGY 



are distinguished with difficulty. The malignant oedema 

 bacillus is actively motile and multi-flagellate and is 

 Gram-positive in the tissues and for the most part in 

 quite young cultures, but in older cultures many indi- 

 viduals are Gram-negative. 



It grows and spores freely on the ordinary culture 

 media. Surface colonies on glucose agar consist of a 

 tangle of filaments which grow out from the centre giving 

 a woolly appearance ; in deep plates and shakes the 

 colonies are similarly woolly. Gelatin is rapidly liquefied, 

 but serum is not liquefied. Milk : acid, slow curdling and 

 some gas. Meat broth : red or pink, rancid, but not 

 putrid, odour. Most of the sugars and salicin are fer- 

 mented but not sucrose, inulin, glycerol, mannitol and 

 dulcitol. 



Pathogenicity . The malignant oedema bacillus is patho- 

 genic for many animals guinea-pig, rabbit, rat, mouse, 

 sheep, goat and horse, but the ox is refractory. The ass, 

 fowl and pigeon are also somewhat susceptible. Different 

 strains vary little in pathogenicity. A lethal dose of 

 culture injected into the thigh of a guinea-pig causes the 

 death of the animal within twelve to twenty -four hours 

 with oedema and the development of gas in the tissues. 

 A sub-lethal dose produces no effect whatever. The 

 muscles affected have a characteristic deep-red colour 

 and are softened, but there is no putrid odour. Grown 

 in a meat broth medium a toxin is formed with which an 

 antitoxin can be prepared. 



Agglutinins for the organism are formed if washed and 

 heated cultures be injected into a rabbit. 



Mixtures of B. perfringens and B. oedematis maligni are 

 very toxic, causing extensive oedema with some gas and 

 very fetid odour. 



Vibrion septique also causes spontaneous infections in 

 animals (p. 525). 



