124 RELATIONSHIPS OF THE COCCACE^E 



Gram. Scum and turbidity appeared in broth (contain- 

 ing cerebro-spinal fluid), and on ascites-agar the organ- 

 ism appeared in small yellowish brown colonies with crystal- 

 line deposits at their margin. The behavior of the coccus 

 in other media, and under the action of various unfavor- 

 able agents, is fully described in the original paper. In 

 general, the meningococcus differs from the gonococcus, 

 culturally, by the fact that it grows more readily on ordi- 

 nary media. In this respect D. W eichselbaumii is in- 

 termediate between D. pneumonia and D. gonorrhoea. 



The meningococcus exhibits a slight degree of virulence 

 for the ordinary laboratory animals, being more patho- 

 genic than D. gonorrhoea but much less pathogenic than 

 the pneumococcus. 



Dr. Wollstein (1907) and other observers have recently 

 shown that D. gonorrhoea and D. W eichselbaumii are 

 closely related in their reactions to immune sera. Agglu- 

 tinins, aggressins, protective power, and amboceptors 

 developed in the bodies of immunized animals are common 

 to the two forms and distinct from the products charac- 

 teristic of Str. pyogenes and D. catarr halts. The better 

 viability of D. W eichselbaumii on culture media and its 

 somewhat higher virulence are the only distinguishing 

 marks of the two species, aside from their differing patho- 

 genic effects in man. 



As in the other types of this genus, a long contest has 

 been waged over the problem of variability among the 

 meningococci. Jaeger (1902) and others claimed to 



