256 EPIDEMIC CEREBRO-SPINAL MENINGITIS 



of complement method was used (p. 131), but now the opsonic 

 index is regarded with more favour as an index of the potency 

 of the serum. Mackenzie and Martin have treated cases by the 

 intra-spinal injection of the fresh serum of patients suffering 

 from the disease or who have recovered from it, such serum 

 being in many cases rich in immune-bodies for the meningo- 

 coccus, and possessing a greatly increased bactericidal action as 

 compared with normal serum. Though the number of cases 

 treated by this method is not yet large,, a distinctly favourable 

 result has been obtained. 



Allied Diplococci. In the naso-pharynx there occur other 

 Gram-negative diplococci which have a close resemblance to 

 the diplococcus intracellularis. These occur in the healthy 

 state, but are especially abundant in catarrhal conditions. Of 

 these the diplococcus or micrococcus catarrhalis has the closest 

 resemblance to the diplococcus intracellularis. In addition to 

 occurring in health this organism has also been found in large 

 numbers in epidemic catarrh. Its microscopic appearances are 

 practically similar to those described above, and it also occurs 

 within leucocytes. Its colonies on serum agar are more opaque 

 than those of the diplococcus intracellularis, and often have a 

 somewhat firm though friable consistence, so that they are some- 

 times removed en masse by the platinum needle. The organism 

 grows on gelatin at 20 C. without liquefying the medium, and 

 it has none of the fermentative properties described above as 

 belonging to the diplococcus intracellularis. The diplococcus 

 pharyngis siccus (v. Lingelsheim) also grows at room tempera- 

 ture, and its colonies are very tough and adhere to the surface 

 of the medium ; it can thus readily be distinguished from the 

 meningococcus. It has marked fermentative properties, acting 

 on glucose, maltose, saccharose, and Isevulose. The diplococcus 

 mucosus has colonies of slimy consistence ; it grows at room tem- 

 perature, and it forms capsules, which can be demonstrated by 

 the method of Hiss. There are other Gram-negative diplococci 

 which are chromogenic, and thus can readily be distinguished. 

 The points of difference between the meningococcus and the 

 gonococcus are given on p. 262. A Gram-positive diplococcus 

 called the diplococcus crassus is also of common occurrence ; it 

 is rather larger than the diplococcus intracellularis, and especially 

 in sub-cultures may tend to assume staphylococcal forms. 



Meningitis due to other Organisms. Apart from the epi- 

 demic form of the disease, meningitis may be produced by almost 

 any of the organisms described in the previous chapter, as 

 associated with inflammatory conditions. A considerable number 



