THE MENINGOCOCCUS 253 



As stated above, the organism occurs in the exudate in the 

 meninges and in the cerebro-spinal fluid, and it can usually be 

 obtained by lumbar puncture. In acute cases, especially in the 

 earlier stages, it is usually abundant ; but in the later stages of 

 cases of more sub-acute character, its detection may be a matter 

 of difficulty, and only a few examples may be found after a 

 prolonged search ; in extremely acute cases also the organism 

 may be difficult to demonstrate. In most cases the disease is 

 practically restricted to the nervous system, but occasionally 

 complications occur, and in these the organism may sometimes 

 be found. It has been observed, for example, in arthritis, 

 pericarditis, pneumonic patches in the lung, and in other 

 inflammatory conditions 



associated with the * ~ 



disease. In a certain ' m f * 



number of cases it has / * . -, * * 



been obtained from the 

 blood during life, but 

 cultures in most in- 

 stances give negative 

 results. 



Experimental inocula- 



tion shows that the > , $ *' ^. - % *, 

 ordinary laboratory ani- 

 mals are relatively insus- 

 ceptible to this organism. 

 An inflammatory condi- ^ J-t* > ^** 



tion may be produced in 



mice and guinea-pigs by FIG. 72. Pure culture of diplococcus iutra- 

 intra - peritoneal injec- cellularis, showiug involution forms. 



tion, and a fatal result 



may follow ; in such cases the organism does not seem to undergo 

 very active multiplication, though it may sometimes be cultivated 

 from the blood, and none of the lesions in the nervous system 

 are reproduced. Flexner and also Stuart M 'Donald have shown 

 that cerebro-spinal meningitis may be produced in monkeys by in- 

 jections of the organism into the spinal canal, the latter observer 

 finding that exudate containing meningococci was more effective 

 than cultures. In such experiments the organism extends up- 

 wards to the brain, and produces meningitis within a very short 

 time. The resulting lesions, both as regards their distribution 

 and general characters, and also as regards the historical changes, 

 resemble the disease in the human subject. Even these animals, 

 however, are manifestly less susceptible than the human subject. 



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