158 ESSENTIALS OF BACTERIOLOGY. 



Pathogenesis. Mice and guinea-pigs die in one or two days 

 after intraperitoneal inoculation. Rabbits usually recover, 

 though lesions analogous to those of human dysentery have 

 been produced. Dogs die in five or six days, with well-marked 

 diarrhoea. 



Products. The patient's blood-serum agglutinates the bacillus 

 in cases in which it can be cultivated from the stools. The re- 

 action is absent from other cases. Shiga has reduced the mor- 

 tality from 34.7 to 9 per cent, by means of a serum obtained 

 from immunized horses. 



Habitat. Found in the stools and in shreds of mucous mem- 

 brane from the intestinal walls. 



Bacillus Aerogenes Capsulatus. (Welch, 1891.) 



Origin. The intestine of man and animals, soil, sewage, and 

 water. 



Form. A thick bacillus, 3 to 6 // in length, frequently capsu- 

 lated. 



Properties. Not motile, anaerobic, forms spores chiefly in cul- 

 tures on blood-serum. 



Growth. Best at 37 C. 



Gelatine. Liquefied slowly or not at all. 



Bouillon. Forms gas. 



Milk. Coagulated and becomes acid. 



Potato. Thin, grayish-white growth with gas-production. 



Forms gas in abundance on dextrose, lactose, or saccharose 

 media. 



Pathogenesis. Is not usually pathogenic for rabbits and mice, 

 though in guinea-pigs and birds it produces "gas phlegmons." 

 It is sometimes found in autopsies on human subjects, produc- 

 ing bubbles or cavities in the viscera (Schaumorgane), but this 

 is probably due to postmortem migration of the germ from the 

 intestine. It has been recovered from the blood during life, 

 however, and. is the most frequent cause of emphysematous 

 gangrene. Various foreign observers have described organisms 

 having similar properties and have given them such names as 

 Bacillus perfringens, Bacillus enteritidis, Granulobacillus immo- 

 bilis, etc., but they were probably dealing with the Bacillus 

 aerogenes capsulatus. 



