I would mention that in typhoid the headache usually ceases when delirium commences, but in this disease it is not so.
BACTERIOLOGY.
It is the presence of Weichselbaum's gram-negative diplococcus in the cerebro-spinal fluid, obtained by lumbar puncture, that clenches the diagnosis, and fulfils all Koch's postulates ; it can be grown outside the body in pure culture, it is capable of producing the disease when injected into susceptible animals, and it can be recovered from the lesions so produced and again cultivated outside the body.
During the first fortnight of the disease the meningococcus can usually be recovered from the naso-pharynx.
The organisms are generally almost entirely iutni-cclhilar, lying within the bodies of the polymorphonuclear leucocytes ; but tlicre are exceptions ; they may be more numerous in the fluid. The number of cocci in the cerebro-spinal fluid varies very much in dil'fei'enl cases, and also in individual cases in the stage of the disease ; though earlier the disease as a rule, the fewer the meningococci.
The differential characters of the meningococcus are : — (a) The majority of strains of meningococci fail to grow on ordinary media at a temperature below 25° C. (b) The meningococcus ferments glucose and miiltose with the production of an acid reaction, but fails to change saccharose. (c) The meningococcus shews positive agglutination with homologous antimeningococcal serum, and has the capacity of removing or absoibing the specific agglutinin from such serum.
The last appears to be the most valuable of available positive tests for identifying the meningococcus. It is necessary, how^ever, to do a control test with normal serum, and also with a suspension of liomologous meningococci.
The specific agglutinating serum used for testing suspect meningo- cocci from the naso-pharynx of contacts should be of proved activity, not only against strains of meningococcus from the same outbreak, but also against strains from the cei-ebro-spinal fluid of recent cases of cerebro-spinal fever in the district where the disease is manifesting itself.
