SERUM REACTIONS 245 



of those suffering from the disease in a considerable number of 

 instances. It has also been obtained from the same positions in 

 healthy individuals, during an epidemic of the disease. In 

 some epidemics also a pharyngitis has been found to occur, and 

 the organism has been obtained from the affected fauces. The 

 majority of workers at this subject are inclined to believe that 

 the organism spreads by means of the lymphatics from the 

 pharynx or nose to the base of the brain, but direct evidence 

 that this occurs has not been supplied. On the other hand, the 

 facts established with regard to other infections make it quite 

 probable that the organism gains entrance to the blood stream 

 from the upper respiratory passages, and then settles in the 

 meninges. Infection by the alimentary canal, the organisms 

 thereafter reaching the spinal meninges by the lymphatics, has 

 been suggested as a possibility, but such a view does not appear 

 to have much support. Whatever may be found to be the path 

 by which the organism reaches the brain, the evidence at 

 present tends to show that the entrance of the organism into 

 the body is by the naso-pharynx, and that this usually results 

 by inhalation of the organism distributed in fine particles of 

 expectoration, etc. In fact, as regards the mode and conditions 

 of infection, an analogy would appear to hold between this 

 disease and influenza. 



Apart from the epidemic form of the disease, cases of sporadic 

 nature also occur, in which the lesions are of the same nature, 

 and in which the meningococcus is present. The facts stated 

 would indicate that the origin and spread of the disease in the 

 epidemic form depend on certain conditions which produce an 

 increased virulence of the organism. We are, however, as yet 

 entirely ignorant as to what these conditions may be. In 

 simple posterior basal meningitis in children a diplococcus is 

 present, as described by Still, which has the same microscopic 

 and cultural characters as the diplococcus intracellularis ; it has 

 been regarded as probably an attenuated variety of the latter. 

 Recently, however, Houston and Ran kin have found that the 

 serum of a patient suffering from epidemic meningitis does not 

 exert the same opsonic and agglutinative effects on the diplo- 

 coccus of basal meningitis as on the diplococcus intracellularis ; 

 and this result points to the two organisms being distinct, 

 though closely allied, species. 



Serum Reactions. An agglutination reaction towards the 

 lijiplococcus intracellularis is given by the serum of patients 

 suffering from the disease, where life is prolonged for a sufficient 

 length of time. It usually appears about the fourth day, when 



