202 INFECTIONS OF THE DIGESTIVE TRACT 



gas production in incubated rabbits is very rapid and is 

 associated with a characteristic sweetish, sickening odor of 

 butyric acid mixed with some unknown constituent or 

 constituents. The gas obtained from the peritoneal cav- 

 ity and connective tissues gives the hydrogen " bark" and 

 burns with a blue flame. The liquefaction of muscles, 

 liver, etc., is remarkably rapid in such incubated rabbits. 

 Grown on pasteurized milk, the bacteria in question induce 

 rapid gas formation ("stormy fermentation") with 

 disruption of curds into small masses and peptonization 

 of casein. They do not quickly produce hydrogen 

 sulphide or methyl mercaptan on ordinary sugar-free 

 media, but may perhaps make these sulphur compounds 

 more readily on milk. Grown in fermentation tubes 

 containing blood bouillon, they rapidly liberate haemo- 

 globin. The organisms are strictly anaerobic and many 

 of their colonies on blood agar appear after two or three 

 days as minute points which lie beneath the surface and 

 develop into fuzzy spheres. These spherical colonies 

 often have dark centers. The microorganisms induce 

 inflammatory necrotic changes with gas formation when 

 injected into susceptible animals, such as pigeons. 



As first shown by Professor Theobald Smith, B. aero- 

 genes capsulatus usually grows readily on bouillon in the 

 closed arm of the fermentation tube provided small 

 bits of sterile, fresh tissue are introduced into it. The 

 liver of the guinea-pig may advantageously be used. 

 The presence of the tissue probably favors the growth 

 in two ways : by furnishing a constituent of the medium 

 necessary for the growth of the organism, and by in- 



