250 EPIDEMIC CEREBROSPINAL MENINGITIS 



preparing sera for other strains which were not agglutinated, he arrived 

 finally at the recognition of four "types" (L-IV.), according to ag- 

 glutinating tests, cross agglutination between them being little marked. 

 Of these, types I. and II. are the commonest, the latter being rather the 

 more frequent. All the strains separated from cases of meningitis have 

 been found to be agglutinated by one of the four sera. The inference is 

 that diplococci otherwise like meningococci, which are not agglutinated by 

 any of the type sera, are without pathogenic significance, and are not 

 accepted as true meningococci. Gordon's results have so far received 

 sound confirmation from the labours of those engaged in the examination 

 of military cases. Manifestly if a strain were isolated from the cerebro- 

 spinal fluid in a case of meningitis which did not conform to any of the 

 types, a new type would have to be added. 



Preparation of Agglutinating Sera. — Hine has devised the following 

 method in the case of meningococci. A rabbit receives on one day three 

 intravenous injections of five hundred millions of dead meningococci, with 

 an interval of an hour between the injections ; six days afterwards it 

 receives a single dose of three thousand-millions. On the eighth day the 

 serum has usually a titre of over 1 : 800. Young rabbits of about a 

 kilogramme in weight give the best results. The sera as supplied by the 

 Central Cerebro-spinal Fever Laboratory are used in four dilutions, to each 

 of which equal amounts of emulsion of th,e organism to be tested are added, 

 the ultimate dilutions of serum being 1 : 50, 1 : 100, 1 : 200, 1 : 400. 

 Emulsions of known type organisms are used as controls at the same time. 

 After the mixtures are made they are put in a chamber at 55° C. for 

 twenty-four hours, and the results are then read. 



Apart from the epidemic form of the disease, cases of a 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 unknown conditions which pro- 

 duce an increased virulence of the organism. 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 pro- 

 bably an attenuated variety of the latter. Houston and Rankin 

 have found that the serum of a patient suffering from epidemic 

 meningitis does not exert the same opsonic and agglutinative 

 effects on the diplococcus of basal meningitis as on the diplo- 

 coccus intracellularis ; and this result points to the two organisms 

 being distinct, though closely allied, species. 



Serum Reactions. — An agglutination reaction towards the meningo- 

 coccus is given by the serum of patients suffering from the disease, when 

 life is prolonged for a sufficient length of time. It usually appears about 

 the fourth day, when the serum may give a positive reaction in a dilution 

 of 1 : 50 ; at a later stage it has been observed in so great a dilution as 

 1 : 1000. Specific opsonins may appear in the blood about the same 

 time, and though they are not always proportional in amount to the 

 agglutinins, the two classes of substances have pretty much the same 



