: )4() MENINGOCOCC US^GONOCOCC US—CA TA RRHA LIS GRO UP 
frequently. Von Lingelsheim^ and Elser and Huntoon- have studied 
these organisms carefully and give the following differential table: 
O C hJ O <5 ^J 02 
Meningococcus — + — — + — — 
Pseudomeningococcus .... — + — — + — — 
Gonococcus^ — + — — — — — 
Micrococcus catarrhalis ... — — — — — — — 
Diplococcus crassus" . . . . + + + + + + + 
Diplococcus flavus — + + — -f- — — 
Micrococcus pharyngis siccus ..— + + — + — — 
Pigmented coccus I....— + + - + — + 
" II .... - + + - + 
"III .... - + - - -^ 
Micrococcus cinereus" ... — — — — — — — 
It will be seen that the meningococcus produces acid from glucose 
and maltose. These fermentation reactions are of greater importance 
in excluding meningococci than for their identification. A differ- 
entiation between the gonococcus, Micrococcus catarrhalis and the 
meningococcus can frequently be made by their growths upon cultural 
media. The gonococcus grows poorly or not at all upon blood serum 
(Loffler's), the meningococcus grows with moderate rapidity upon it, 
and Micrococcus catarrhalis grows even upon plain agar. 
The final diagnosis of the meningococcus depends upon its agglu- 
tination with specific sera. Sera specific for each of the four groups 
or types should be available. Polyvalent sera are rather less satis- 
factory. The titer should be at least -^^-q, and yoVo" is preferable. 
The controls should include normal horse serum diluted 5^. No 
agglutination should occur in this test. Agglutination should be 
carried out in a water-bath heated to 55° C. At least twelve hours' 
incubation should be allowed before the results are read. Positive 
agglutination will take place in dilutions of 1 to 50, even in 1 to 1000. 
Kutscher'^ has isolated strains of the organism which failed to aggluti- 
nate (macroscopic method) at 37° C, but agglutinate typically at 
55° C. Agglutinating sera frequently may be used for complement- 
fixation tests with autolyzed meningococci as antigen. 
Serological Diagnosis.— Bettencourt and Fran (,'a,^ von Lingelsheim,'" 
Elser and Huntoon^' and others have shown that the sera of con- 
1 Klin. Jahrb., 1906, 15, Heft. 2, 373. '- Jour. Med. Res., 1909, 20, 371. 
3 "-(-" = Gram-positive. "— " = Gram-negative. 
4 "_j_" = acid produced. "— " = no acid produced. 
s According to Watabiki, each of 15 gonococcus strains studied fermented glucose, 
maltose and dextrin. Levulose was doubtfully acidified. (See Jour. Med. Res., 1909, 
20, 365.) 
« Jaeger's meningococcus. ^ Micrococcus catarrhalis? 
8 KoUe and Wassermann: Handb. d. path. Mikroorganismen, I. Erganzbd., 1907, 
p. 518. 
9 Ztschr. f. Hyg., 1904, 46, 463. i" Klin. Jahrb., 1906, 15, No. 2. 
'1 Loc. cit. 
