Food Poisons 



2SS 



Morphology.' — It is a large bacillary organism of a somewhat 

 quadilateral shape with rounded corners or sometimes with entirely 

 rounded ends, usually single or in pairs, and only in old cultures 

 with numerous involution forms occurring in the form of filaments. 

 It measures 4 to 6^ X 0.9 to 1.2//. 



Motility. — The motility is sluggish. There are per itrichial flagella, 

 but not usually more than eight. 



Sporulation. — The bacillus forms good-sized oval spores that 

 are situated near one end and slightly increase the diameter of the 

 rod at that point. No distinct drum-stick appearance occurs. 

 The spores are killed by exposure to 8o°C. for an hour. 



Staining.' — The organism stains well by ordinary methods, and by 

 Gram's method. It is not acid-fast. 



Cultivation. — Bacillus botulinus is a strict anaerobe, and when 

 appropriate conditions are present, grows readily upon nearly any 

 culture-medium. The best development takes place at tempera- 

 tures ranging from 18° to 25°C. As it liquefies gelatin, it is recom- 

 mended that its isolation be undertaken upon slightly alkaline dex- 

 trose gelatin, kept at 25°C. 



Colonies. — Colonies appear under anaerobic conditions and are 

 round, translucent, pale, yellow-brown and coarsely granular. After 

 some hours a Kquid zone surrounds the colony, and as the lique- 

 faction of the gelatin continues, the coarse grantiles keep up a 

 constant slow streaming movement. When the maximum size is 

 attained, the colonies become brown and opaque. 



Bouillon. — In plain bouillon a slight turbidity can be observed in 

 twenty-four hours. In glucose broth there is a dense turbidity. 



Agar-agar. — The surface growth is rarely seen because of the 

 strict anaerobic conditions required. Colonies are in general round, 

 granular and yellowish-brown. 



Gelatin. — ^Liquefaction begins to take place in a few hours and 

 progresses slowly. 



Mica. — Slight acidulation occurs without coagulation or pepton- 

 ization. Acid is produced. 



Metabolic Products. — ^It liquefies gelatin through the formation 



of a gelatinase that appears in bouillon and solid cultures. It 



• ferments dextrose -with the production of CH4,C02 and H. Butyric 



acid is given off from appropriate substrata. It also forms a very 



powerful exotoxin that saturates the fluids of the culture-media. 



Toxin. — This is best prepared for study by cultivation in a sugar- 

 free bouillon at 25°C. for two weeks and then filtering through sterile 

 porcelain; 0.00 1 cc. of such a medium kills guinea-pigs in from 

 three to four days. Rabbits are also susceptible and not only die 

 when subcutaneously injected, but also if fed upon food to -which 

 0.1 to 0.5 cc. of the toxin has been added. The toxin is poisonous 

 to man, monkeys, kittens, rats, white rats, mice, and rabbits. 

 The toxin is destroyed by 8o°C. in thirty minutes. 



