516 



PATHOGENIC MICROORGANISMS 



In spinal fluid satisfactory preparations may be obtained by 

 staining in Jenner 's blood stain. Councilman, Mallory, and Wright 7 

 were the first to notice that, when stained with Loeffler 's methylene- 

 blue, meningococcus stains irregularly, showing metachromatic gran- 

 ules in the center of the cell bodies. These granules can be demon- 

 strated more clearly with the Neisser stain employed for similar 

 demonstration in the case of B. dipththeriae and have some value in 

 differentiating meningococcus from gonococcus. 



RT ' J 



*** * .*>* 



** V ** V * 



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FIG. 55. MENINGOCOCCUS PURE CULTURE. 



It is important to remember that meningococci in spinal fluid 

 undergo solution very readily, a solution which is probably an 

 autolysis, with the result that spinal fluid which may be full of 

 polymorphonuclear leucocytes, contains very few recognizable or- 

 ganisms. This readiness of meningococci to go into solution will be 

 spoken of below in connection with problems of cultivation. 



Cultivation of the Meningococcus. The meningococcus is peculiar 

 in that there is considerable difference in the ease with which separate 

 strains can be made to grow upon artificial media. Some meningo- 

 cocci grow readily upon all meat infusion culture media. They may 

 even grow upon some meat extract media, but growth upon these is 

 never profuse. It is never well to rely upon media to which no 

 enriching substance has been added, or that have not been especially 

 made for meningococcus cultivation when attempts are made at first 



7 Councilman, Mallory , and Wright, Eep. Mass. State Bel. of Health, 1898. 



