THE MENINGOCOCCUS GROUP 



293 



The organisms are non-motile and possess no flagella. No spores 

 are formed and no capsules have been demonstrated. (Jaeger 1 

 believed that the organisms produced capsules, but his observations 

 are unconfirmed.) Ordinary anilin dyes stain meningococci, but quite 

 irregularly. Occasionally one element of a pair stains intensely 

 while its fellow stains faintly or not at all. Relatively large oval 

 or round forms are frequently seen in cultures and in purulent exudates 

 as well, which exhibit a brightly staining point in the centre of the 

 organism; the remainder of the cell is scarcely colored. 2 Carbol- 

 thionin is one of the best stains for the organism. The meningococcus 



FIG. 39. Meningococci in pus. X 1000. 



is Gram-negative. Meningococci obtained from purulent exudates 

 or from cultures on artificial media can not be definitely differentiated 

 from gonococci or even from Micrococcus catarrhalis by any known 

 staining methods. The source of the material should be known before 

 even a tentative morphological diagnosis is attempted. 



Isolation and Culture. The meningococcus grows feebly or not at 

 all upon ordinary artificial media. Growths may be obtained upon 

 agar containing animal protein, as defibrinated blood or ascitic fluid, 

 or upon Loffler's blood serum by smearing cerebrospinal fluid (drawn 

 with aseptic precautions by lumbar puncture) in liberal amounts 

 upon the surface of these media. 3 The addition of 1 per cent, of 

 dextrose to the media favors development of the cocci. If the fluid 

 obtained is not turbid, centrifugalization should be resorted to and 



1 Zeit. f. Hyg., 1895, xix, 358. 



2 Councilman, Mallory and Wright, loc. cit., p. 74. 



3 For technic of lumbar puncture, see page 220. 



