MENINGITIS DUE TO OTHER ORGANISMS 253 



cases with head symptoms we have found it present where there 

 was merely a condition of congestion. Occasionally epidemics 

 of meningitis have been due to the pneumococcus. The pnewino- 

 bacillus also has been found in a few cases. Meningitis is not 

 infrequently produced by streptococci, especially when middle-ear 

 disease is present, less frequently by one of the staphylococci ; 

 occasionally more than one organism may be concerned. In 

 meningitis following influenza the influenza bacillus has been 

 found in a few instances, but sometimes the pneumococcus is the 

 causal agent. Sporadic cases of meningitis occur associated with 

 organisms which resemble the influenza bacillus morphologically 

 and also in presenting hemophilic culture reactions, but which 

 possess pathogenic properties for rabbits and guinea-pigs. Both 

 in the cerebro-spinal fluid and in cultures, these bacilli frequently 

 show a tendency to produce long filamentous forms and also may 

 show a beading of the protoplasm, which gives them a diph- 

 theroid appearance. The cases from which such bacilli have 

 been isolated have chiefly occurred in children, are extremely 

 fatal, and probably often follow on an otitis media, from which 

 condition similar organisms have been isolated. Sometimes the 

 meningitis is part of a septicemic or pysemic process, — in the 

 latter the joints are often affected. It is impossible at present 

 to say whether the organisms associated with such conditions 

 are true influenza bacilli or are merely allied to them. They 

 certainly tend to be more widely distributed in the body of the 

 infected individual than is the case in the disease known clinically 

 as influenza. On the other hand, influenza appears under several 

 forms, and considerable variations may exist in the virulence 

 of strains responsible for different outbreaks. An invasion of 

 the meninges by the anthrax bacillus occurs, but is a rare 

 condition ; it is attended by diffuse haemorrhage in the sub-arach- 

 noid space. In tubercular meningitis the tubercle bacillus, of 

 course, is present, especially in the nodules along the sheaths of 

 the vessels. 



In conclusion, it may be stated that mixed infections may occur 

 in meningitis. Thus the pneumococcus has been found associ- 

 ated with the tubercle bacillus and also with the meningo- 

 coccus, sometimes appearing as an additional infection to the 

 latter. 



Methods of Examination. — During life these involve the 

 microscopic investigation of the centrifuged cerebro-spinal fluid 

 and making cultures therefrom (p. 245). For the former, smears 

 stained by carbol-thionin-blue and by Gram's method make 

 the recognition of the meningococcus relatively easy, and the 



