MENINOOCOCCU8. 557 



influenza occurs during the course of the diseases 

 caused by the corresponding micro-organisms. 



Previous to 1887 diplococci resembling the pneu- Micrococcus 



,, -i , Meningitidis. 



mococcus had been found in the exudate in cases 

 of cerebrospinal meningitis by Foa and Bordoni- 

 Uffreduzzi, by Fraenkel and others. Weichsel- 

 baum made similar observations during the same 

 year, and in addition described six cases in which 

 a diplococcus of another nature was present in 

 pure cultures. To the latter he gave the name of 

 Diplococcus intracellularis meningitidis. Exten- 

 sive observations by others, both in Europe and 

 America (Councilman, Mallory and Wright, and 

 others), revealed the presence of the last-named 

 organism in many instances, and showed that it is 

 the most common cause of epidemic cerebrospinal 

 meningitis. 



The meningococcus resembles the gonococcus 

 closely in that it is usually found in biscuit-shaped 

 pairs, nearly always within pus cells, and does not 

 stain by Gram's method (Weichselbaum). It is 

 properly to be called a micrococcus since it divides 

 in two transverse directions (Albrecht and Ghon) ; 

 tetrads, small groups and short chains are some- 

 times seen. However, it forms no striking chains, 

 is non-motile and produces no spores. Growth 

 may be obtained on some of the ordinary media 

 (glycerin agar), in which the organism differs 

 from the gonococcus, but a medium which contains 

 blood or serum is much more favorable. It is an 

 obligate aerobe, grows best at the body tempera- 

 ture and virulence is soon lost under artificial 

 conditions. 



It produces a membrane on meat broth with viability. 

 clouding of the medium. Viability is retained 



