BACILLUS (EDEMATIENS 453 



with several non-fatal doses of cultures sterilised by heat or freed 

 from the bacilli by filtration, immunity against the living organ- 

 ism could be developed in a comparatively short time. They 

 found that the filtered serum of animals dead of the disease 

 is more highly toxic, and also gives immunity when injected 

 in small doses. These experiments were confirmed by 

 Sanfelice. 



Bacillus CEdematiens. 



This organism, first described by Weinberg and Seguin, has the 

 following characters. It is a fairly large bacillus, of about the 

 same size as the b. welchii, but tending to be rather longer. It 

 is distinctly pleomorphous, often occurring in C and S forms, 

 and growing also in chains. It is Gram-positive, but Gram- 

 negative forms are found in older cultures. It possesses numer- 

 ous lateral flagella, though in ordinary conditions motility is 

 practically absent. Spore-formation occurs, the spores being 

 usually subferminal in position. 



Cultivation. — The organism grows well on all the ordinary 

 media down to a temperature of about 20° C, but only under 

 strict anaerobic conditions. On solid media the deep colonies 

 are small, somewhat irregular balls with woolly margin, while 

 the superficial ones are film-like with wavy border. In glucose- 

 bouillon there is produced at first a general turbidity, but this 

 soon clears off, leaving only a slight deposit at the bottom of the 

 tube ; this is "due to the rapid disintegration of the bacilli, the 

 deposit being formed chiefly of spores. In milk it causes the 

 formation of a loose acid clot, which falls to the bottom as a 

 grumous deposit ; there is no digestion of the casein, nor is 

 there any liquefaction of gelatine or digestion of coagulated 

 serum. It actively ferments nearly all the ordinarily used 

 sugars with evolution of gas. 



In cooked meat medium it produces a pink colour, which 

 afterwards fades almost to a white, and there is slight formation 

 of gas. The bacillus may thus be regarded as belonging to the 

 saccharolytic type of anaerobes. 



Pathogenic Effects. — In a series of cases of gas gangrene 

 Weinberg found the b. oedematiens to occur next in order of 

 frequency to the b. welchii, and he considers it to be the most 

 important agent in what he calls the "toxic form" of gas gan- 

 grene. This type is characterised by a rapidly spreading 

 gelatinous oedema, with little or no gas formation, and by 

 severe symptoms of general poisoning. Blood culture usually 

 gives a negative result, though the bacillus may be found in the 



