538 NEISSERIA 



bator. To conserve the virulence of the organisms they should be subcultured 

 every two days on blood agar slopes, or preferably frozen and dried. 



The meningococcus undergoes rapid autolysis ; this is responsible for the 

 swelling and loss of staining properties in cultures more than a few hours old. 

 This property is destroyed by heating to 65° C. for 30 minutes. If the organisms are 

 suspended in saline, covered with toluol to prevent contamination, and incubated 

 at 37° C, autolysis is said to be nearly complete in 4 hours (Flexner 1907a). For 

 this reason all suspensions intended for agglutination should be inactivated by heat. 



Antigenic Structure. — Soon after the agglutination test was introduced for the identifica- 

 tion of meningococci, it was noticed that different strains possessed varying degrees of 

 agglutinabiUty. Kutscher (1906), who employed the absorption test, observed that there 

 was a marked difference between strains isolated from different sources, but he was 

 unable to classify them by this method. In 1909 Elser and Huntoon found that 40 per cent, 

 of meningococci were inagglutinable by a monovalent serum, and that these inagglutinable 

 strains, which they term pseudo-meningococci, exhibited a reduced absorption capacity ; 

 they further divided the pseudo-meningococci by absorption into two sub-groups. In 

 the same year Dopter ( 1909) noticed the presence in nasopharyngeal mucus of cocci resem- 

 bling the meningococcus in morphology, cultural and fermentation reactions, but differing 

 from it in their complete absence of agglutination with a meningococcal serum ; these 

 organisms he termed parameningococci. Arkwright, also in 1909, studied 25 strains of 

 meningococci from cases occurrmg in epidemic areas, and 20 strains from sporadic cases ; 

 he noticed not only that by agglutination and absorption the organisms could be roughly 

 divided into groups, but that, serologically, the sporadic strains tended to deviate more 

 from the type to which most strains conformed than did the epidemic strains. In 1914 

 Dopter and Pauron divided the parameningococci into 3 types, a, ^, and y. Soon after the 

 commencement of the War, Ellis (1915) examined 46 strains from 6 epidemic foci, and found 

 that they fell by agglutination into 2 types, I and II, of which Type II was probably identical 

 with Dopter's parameningococcus. Simultaneously Arkwright (1915) was able to classify 

 30 out of 35 strains from epidemic cases into 2 main groups. Types I and II, of which Type 

 II, like EUis's Type II, corresponded to Dopter's parameningococcus ; of the remaining 

 5 strains, 3 were difficult to classify by agglutination, and 2 were intermediate between 

 the two types. Gordon and Murray (1915) by using the absorption test found that 32 

 strains from the cerebrospinal fluid of epidemic cases fell sharply into 4 groups, which 

 they called Groups I, II, III, and IV ; none of these groups, however, showed any relation 

 to Dopter's parameningococcus. In 1917 NicoUe, Debains and Jouan (1918), using the 

 agglutination test alone, were able to classify the meningococci into 4 types, called A, B, C 

 and D. Gordon and Murray's Type I and III strains, as they ai'e now generally referred 

 to, corresponded to Dopter's Meningococcus and to NicoUe, Debain and Jouan's Type A, 

 and their Type II and IV strams to Nicolle, Debain and Jouan's Type B. F. Griffith 

 (1917), working at the Local Government Board laboratories, was able to divide his 

 meningococci into two main groups by simple agglutination. Groups I and II ; his Group I 

 corresponded roughly with Gordon and Murray's Types I and III, and his Group II with 

 their Types II and IV. Scott (1917) similarly found that his strains fell into two groups. 



Since 1918 observations, particularly in the United States, have served to 

 show that no sharp line of demarcation can be drawn between different types of 

 meningococci. Branham, Taft and Carlin (1931) and Branhain (1932), it is true, 

 were able to assign every one of 221 strains of meningococci isolated during a 

 time of epidemic prevalence to one or other of Gordon and Murray's four types, 

 but this was possible only after prolonged study involving examination of their 

 agglutinabiUty, their power to absorb agglutinins, and their agglutinogenic capacity. 

 The lack of strict type specificity, and the readiness with which many strains 



