246 CLINICAL BACTERIOLOGY. 



are intended for consumption after a considerable length of 

 time, and that, according to Van Ermengem, are, by reason 

 of their mode of preparation, exposed to the danger of 

 undergoing anaerobic fermentative processes. Van Ermen- 

 gem believes the actual cause to be the anaerobic bacillus 

 botulinus, which he isolated in the epidemic at Ellezelles 

 from a piece of ham that gave rise to typical cases of in- 

 toxication. As opportunity has not been afforded since 

 Van Ermengem made his communication for investigating 

 cases of botulism, the following description will closely 

 follow his statements. 



Fig. 54. Bacillus botulinus ; eight-day culture in glucose-gelatin ; X 1000 (Van 

 Ermengem). 



Morphology of the Bacillus Botulinus (Fig. 54). The 

 bacillus is a large, slightly motile rod, from 4 to 6/j. long and from 

 0.9 to 1.2 IJL thick, with slightly rounded extremities, and possess- 

 ing from 4 to 8 flagella. The formation of filaments is but 

 rarely observed ; more frequently involution -forms are present, 

 the bacilli becoming smaller, presenting deficiencies, and being 

 at times arranged in filaments. Both in cultures and in the 

 body the bacillus botulinus generates spores of oval form, gen- 

 erally polar, rarely central, and exceeding the thickness of the 

 bacillus. The bacillus is readily stained, and also by Gram's 

 method, but the exposure to alcohol must not be too protracted. 



Cultural Peculiarities. The temperature-optimum is be- 

 tween 20 C. (68 F.) and 30 C. (86 F.). Below a temper- 

 ature of 16 C. (60.8 F.) the bacillus botulinus grows but 

 slowly, while above 35 C. (95 F.) it no longer generates 

 spores, does not itself thrive so well, and exhibits involution- 



