246 EPIDEMIC CEREBRO-SPINAL MENINGITIS 



the serum may give a positive reaction in a dilution of 1 : 50 ; 

 at a later stage it lias 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 significance, and may occasionally be of 

 use in diagnosis when lumbar puncture fails to give positive 

 results. Although their presence in large amounts may be said 

 to indicate a marked reaction, they do not supply information of 

 much value in relation to prognosis. Immune-bodies, as shown 

 by bactericidal and deviation of complement tests (p. 126, 130), 

 may also be developed in considerable amount in the course of 

 the disease. 



Anti-sera for therapeutical purposes have been introduced by 

 various workers, and of these the one which has been most 

 extensively used is that of Flexner and Jobling. This serum 

 is prepared from the horse by repeated injections in increasing 

 doses of dead cultures, followed by injections of culture autolysate 

 and of living cultures, these two latter being best administered 

 by the subcutaneous method. Several strains of meningococci 

 are mixed together for purposes of injection, and the immunisa- 

 tion is continued over a period of several months. For treat- 

 ment of the disease the serum is injected under the spinal 

 dura, 30 c.c. being generally used for an injection, this being 

 continued for several days. This serum has been used on a 

 large scale in various parts of the world, and there is general 

 agreement as to its favourable effects the mortality of the 

 disease, which is generally 70 to 80 per cent., having been 

 reduced to about 30 per cent, or even less. By means 

 of its use the tendency to the occurrence of chronic lesions 

 has also been markedly diminished. The action of such 

 anti-sera cannot as yet be fully explained. They certainly 

 contain opsouins, agglutinins, immune-bodies which bind com- 

 plement, and possibly also anti-endotoxins. After the injection 

 the number of meningococci becomes markedly reduced, 

 probably as a result of increased phagocytosis; there can 

 scarcely be any direct bactericidal action owing to the absence 

 of complement. The standardisation of such anti-sera is a 

 matter of some difficulty ; at first the deviation of complement 

 method was used (p. 130), 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 



