MICROCOCCUS INTRACELLULARIS MEN1NGITIDIS 523 



way, but somewhat more closely than are the different members of the 

 viridans group of streptococci, a point which makes it plain that a 

 diagnostic or curative serum, to be truly polyvalent, must be produced 

 with many different representatives of organisms isolated from cases. 

 The correspondence of the different types, as named in various coun- 

 tries, is as follows: 



Gordon's type I = para-meningococcus 



Gordon's type II = normal meningococcus 



Gordon's types III and IV = intermediate or irregular strains, 



of which there are a considerable number of different ones, 



shading into each other, serologically. 



As far as the prevalence of type is concerned, no definite rule can 

 be established at present. In the extensive investigations of Gordon 

 and his co-workers, it was found that the earliest cases were mostly his 

 type I, later came his type II, especially in the London district, and 

 after March type IV cases began to appear, but no type III cases were 

 noticed until July. 



Agglutination. Immunization of animals by repeated inocula- 

 tions of meningococcus 25 results in the formation in the blood serum 

 of agglutinins. Kolle and Wassermann 26 obtained from horses a 

 serum which had an agglutinating value of 1 :3,000 for the homol- 

 ogous strain, and of as much as 1 :500 for other true meningococcus 

 strains. Similar experiments by Dunham 27 and others have proved 

 the unquestionable value of agglutination for species identification 

 of this group. Great differences may, however, exist between indi- 

 vidual races in their agglutinability in the same immune serum. 



Kutscher has recently called attention to the fact that strains 

 which cannot be 'agglutinated in specific sera at 37 C. will often 

 yield positive results when subjected to 55 C., a fact of some prac- 

 tical importance if confirmed. 



Elser and Huntoon 28 have shown that in the serum of infected 

 human subjects agglutination of some strains takes place in dilutions 

 as high as 1 :400. 



The Production of Agglutinating Sera for Meningococcus Deter- 

 mination in Laboratories. For this purpose, rabbits are best 



K Albreclit and Ghon, Wien. klin. Woch., 1901. 



26 Kolle und Wassermann, Deut. med. Woch., 15, 1906. 



27 Dunham, Jour. Inf. Dis., 11, 1907. 



28 Elser and Huntoon, loc. cit. 



