PATHOGENIC BACTERIA. 



267 



Bacillus aerogenes capsula- 

 tus. — ^A thick bacillus, 3 to 6 /i 

 in length, frequently capsulated, 

 discovered by Welch and Nuttall. 

 The capsules may be found in 

 preparations from animal tissues, 

 but rarely in cultures. It some- 

 times forms spores, chiefly in 

 cultures on blood-serum. The 

 vegetative forms are destroyed at 

 58° C. moist heat in ten minutes, 

 but the spores withstand boiHng 

 nearly eight minutes. It is not mo- 

 tile. It stains by Gram's method. 

 It is anaerobic, and is readily 

 cultivated by Buchner's method 

 for anaerobes. It grows best 

 at the body temperature, but 

 will grow at the room tempera- 

 ture. It may hquefy gelatin 

 slowly or not at all. The 

 growths are whitish. In media 

 containing lactose, dextrose or 

 saccharose it produces an abun- 

 dance of gas; but according to 

 Welch, it is also able to form 

 gas from proteids. Milk is co- 

 agulated, and the reaction be- 

 comes acid. Gas forms upon 

 potato, where the growth is 

 thin and grayish-white. 



It occurs in the intestine of 

 man and various other animals, 

 in soil, sewage and water. It is 



Fig. 73. — Bacilltjs aero- 

 genes CAPSUIATUS, CULTURE IN 

 DEXTROSE-AGAR, SHOWING GAS- 

 BUBBLES. 



