494 A MANUAL OF BACTERIOLOGY 



In culture, it forms short and long rods and short 

 filaments. 



Cultural characters. B. influenzce is aerobic, but will 

 also develop anaerobically (Fildes), and no growth occurs 

 on media at 22 C. On glycerin-agar and blood-serum at 

 37 C. it forms very small, discrete, transparent, drop-like 

 colonies in from twenty-four to forty-eight hours. There 

 is no growth on potato. The organism grows best on 

 media containing blood, such as agar smeared with 

 sterile rabbit's, or, better, pigeon's blood, or on agar with 

 blood and boiled. Unaltered human blood is actually 

 inhibitory. In broth it grows at the surface in fine 

 white flakes which subsequently sink. 



It usually soon dies out in cultivation, but according 

 to Klein can be kept alive for some weeks in gelatin 

 incubated at 37 C. Fleming recommends the minced 

 meat broth used for growing anaerobes ; in this it 

 remains alive for six weeks or more. Preparations from 

 cultures show long twisted chains and threads of bacilli, 

 aggregated so as to form dense networks and convolutions. 

 These chains or threads are composed of bacilli placed 

 end to end, and united by a continuation of the cell- 

 membrane. Involution forms occur. It is stated to grow 

 better in association with the M . pyogenes var. aureus 

 than alone. The organism does not seem to be able to 

 live outside the body for any length of time, and is 

 readily destroyed by desiccation, weak antiseptics, and 

 by a temperature of 60 C. acting for five minutes. 



Pathogenic action. According to Pfeiffer the bacillus 

 is pathogenic to monkeys and rabbits. Klein, however, 

 was unable to obtain any definite effects in these animals 

 by the injection either of sputum rich in bacilli or of pure 

 cultures. In general, suspensions of bacilli from solid 

 cultures have little effect on laboratory animals ; intro- 

 duced into the peritoneal cavity, a certain amount of 



