DIPLOCOCCUS INTRACELLULARIS MENINGITIDIS. 179 



fours. It is readily stained with the anilin dyes, especially 

 Loeffler's alkaline methylene-blue, and is decolorized by 

 Gram's stain. It does not form spores, has no flagella, and 

 is not motile. It differs from the gonococcus in that it is 

 very easily cultivated. 



The meningococcus grows well on agar-agar and on glycerin- 

 agar, but not on potato, nor in gelatin or bouillon. It grows 

 very luxuriantly on Loeffler's blood-serum mixture, but not 

 at all in a mixture of bouillon and blood-serum. It abso- 

 lutely requires a temperature equal to that of the body. It 

 is a facultative anaerobe. 



In tube cultures it forms minute round colonies having a 

 very sharply defined regular border. The colonies are shin- 

 ing and almost translucent, and of a grayish-white color. 

 They very closely resemble streptococcus colonies on an agar 

 slant. The medium is not liquefied. 



On agar-agar tubes or plates deep and superficial colonies 

 are formed. The deep colonies are hardly visible. The 

 superficial colonies are round, flat, and very finely granular, 

 with dentate edges. They are yellowish-brown in color, and 

 darker in the centre than at the periphery. 



The meningococcus possesses very little resistance to either 

 heat or chemicals, and dies very rapidly in culture unless 

 frequently transplanted. 



Pathogenesis : The meningococcus is pathogenic for man 

 and animals. Weichselbaum concluded that infection occurred 

 through the ear and upper air-passages, especially the nose. 

 He succeeded in obtaining the diplococcus in pure culture 

 from the nasal secretions of one case out of his series of six. 

 It has also been found in the nares of healthy individuals and 

 in a few cases of conjunctivitis. It has been found present 

 in about 50 per cent, of all cases of cerebrospinal meningitis. 



The bacteriologic diagnosis is made by examining the fluid 

 obtained from the spinal canal by means of lumbar puncture. 

 Park says that such a diagnosis is of clinical value, because 

 about 40 per cent, of all cases of meningitis due to this coccus 

 recover, while nearly all the cases due to the pneumococcus 

 and streptococcus end fatally. 



Cultures may also be made from the pus obtained from the 



