THE ANAEROBIC BACILLI 741 



organism from the stomach and spleen of one of those who died 

 of the infection. The results of Van Ermengem have been confirmed 

 by Romer, 43 and others. 



Morphology and Staining. Bacillus botulinus is a large, straight 

 rod with rounded ends, 4 to 6 micra in length by 0.9 to 1.2 micra 

 in thickness. The bacilli are either single or grouped in very short 

 chains. Involution forms are numerous on artificial media. The 

 bacillus is slightly motile and possesses from four to eight undulated 

 flagella, peripherally arranged. Spores are formed in suitable media, 

 most regularly in glucose-gelatin of a distinctly alkaline titer. The 

 spores are oval and usually situated near the end of the bacillus, 

 rarely in its center. Spores are formed most abundantly when 

 cultivation is carried out at 20 to 25 C., and are usually absent 

 when higher temperatures are employed. 



The bacillus is easily stained by the usual aqueous anilin dyes, 

 and retains the anilm-gentian-violet when stained by Gram. It is 

 necessary, however, in carrying out Gram's stain to decolorize care- 

 fully with alcohol since overdecolorization is easily accomplished, 

 leaving the result doubtful. 



Cultivation. The bacillus is a strict anaerobe. In anaerobic en- 

 vironment it is easily cultivated on the usual meat-infusion media. 

 It grows most readily at temperatures about 25 C., less luxuriantly 

 at temperatures of 35 C. and over. 



The bacillus is delicately susceptible to the reaction of media, 

 growing only in those which are neutral or moderately alkaline. 



In deep stab cultures in one per cent glucose agar, growth is at first 

 noticed as a thin, white column, not reaching to the surface of the 

 medium. Soon the medium is cracked and split by the abundant 

 formation of gas. On agar plates, the colonies are yellowish, 

 opalescent, and round, and show a finely fringed periphery. 



On gelatin, at 20 to 25 C., growth is rapid and abundant, and 

 differs little from that on agar, except that, besides the formation 

 of gas, there is energetic fluidification of the medium. On glucose- 

 gelatin plates, Van Ermengem describes the colonies as round, yel- 

 lowish, transparent, and composed of coarse granules which, along 

 the periphery in the zone of fluidification, show constant motion. 

 The appearance of the surface colonies on glucose-gelatin plates is 

 regarded by the discoverer as diagnostically characteristic. 



43 Romer, Cent, f . Bakt. xxvii, 1900. 



