GROUP OF SPORE-BEARING ANAEROBES 365 



peritrichic flagella. Capsules have not been demonstrated. Oval 

 spores, somewhat greater in diameter than the bacillus, are pro- 

 duced at the poles. The organism stains readily with the anilin 

 dyes and is gram-positive. 



Isolation and Culture. The colonies on dextrose gelatin are 

 at first circular, transparent, light yellow, and soon liquefy the 

 gelatin. Under the low power of the microscope they appear to 

 consist of granules in constant motion. Later the colonies become 

 brown and opaque. Milk is not curdled. 



Physiology. The organism is an obligate anaerobe. Its 

 optimum-growth temperature is 18 to 20. It grows little, if 

 at all, at blood-heat, and when developing at this temperature, 



Fig. 154. Bacillus botidinus (van Ermengem in Kolle and Wassermann) . 



produces numerous involution forms. Gas is produced from dex- 

 trose, but not from saccharose or lactose. Acid, in part butyric, is 

 produced in dextrose media. 



Pathogenesis. Injections of the organism into the body of 

 laboratory animals have revealed the fact that the organism is 

 pathogenic only by virtue of the toxins that are elaborated out- 

 side of the body. It does not increase in numbers in the tissues. 

 Probably this may in part be accounted for by its normal optimum- 

 growth temperature. The toxin produced, on the other hand, is 

 very poisonous, whether injected or ingested. The use of raw or 

 imperfectly cooked animal foods may give rise in man to the 

 symptoms of botulism in the course of twenty-four to thirty-six 

 hours, often with fatal termination. 



