112 THE POSSIBLE OCCURRENCE OF [ch. viii 



9 per cent, (out of 36 cultures) failed to produce acid in 

 dextrose. Summers and Wilson (1909) state that out of 

 80 strains "nearly all" fermented the usual sugars but a 

 few gave the fermentation reactions of Mic, cata/rrhalis. The 

 organism isolated from sporadic cases of meningococcal menin- 

 gitis shows such marked differences in its sugar reactions 

 when compared with a typical meningococcus that some 

 writers regard it as a distinct species (Batten). Arkwright 

 (1909), though he refutes this, acknowledges that the sporadic 

 type is less uniform in its fermenting powers. Some of his 

 strains of meningococcus permanently failed to ferment any 

 sugars; others, which failed to do so when first examined, 

 gradually acquired the power in the course of many months ; 

 others, again, which did ferment sugars, completely lost this 

 property after cultivation for a certain time. Another interest- 

 ing fact, in this connection, is mentioned by Andrew Connal 

 (1910), namely that in the late, chronic stages of cerebrospinal 

 fever the meningococcus isolated from the cerebrospinal 

 fluid is found to have lost its power to break up sugar. 

 Mic. catarrhalis on the other hand may acquire power to 

 ferment sugars. Gordon (quoted Martin, 1911) found that, 

 out of 25 strains examined by him, three fermented dextrose, 

 saccharose, galactose and maltose. 



The meningococcus and Mic. catarrhalis differ in virulence 

 but this property in the latter can be artificially raised by 

 "passage." 



As regards pathogenesis, this distinction, again, between 

 the two organisms sometimes breaks down, symptoms typical 

 of infection by one organism being in reality due to infection 

 by the other. The symptoms attributable to Mic. cata/rrhalis 

 infection differ widely. Thus it may cause an acute pharyn- 

 gitis (Gordon, 1906) or a tonsilitis; it may cause a "common 

 cold" or give rise to an infective cold and sore throat spreading 

 from person to person (Allen, 1908); it may set up otitis 

 media and a secondary meningitis (Barker, 1908), or, again, a 

 primary meningitis (Arkwright and Wilson) or, finally, an 

 epidemic so closely resembling cerebrospinal fever in its 

 symptoms that this disease has actually been diagnosed until 



