560 PATHOGENIC MICROORGANISMS 



develop at temperatures below 20 C., while meningococcus will not 

 grow at temperatures below 25 C. 30 



Dunham, 31 who has recently made a comparative study of meningo- 

 coccus and other Gram-negative diplococci from the nose and throat, 

 states that while some of the supposed Micrococcus catarrhalis cultures 

 are easily distinguished from meningococcus simply by the character- 

 istics of their growths upon two-per-cent glucose agar, others offer great 

 difficulties to differentiation. He recommends as a differential medium 

 a mixture of sheep serum and bouillon containing 1 per cent of glucose. 

 Upon this medium all true meningococci produce acid, but no coagula- 

 tion, within twenty-four hours. Cultures from the nose and throat, 

 however, produce acid and coagulation, or else produce an alkaline 

 reaction. 



30 Weichselbaum, in Kolle und Wassermann, Bd. iii, p. 269. 



31 Dunham, Jour. Inf. Dis., 1907. 



