SERUM REACTIONS 255 



diplococcus intracellularis is given by the serum of patients 

 suffering from the disease, where 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 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 (pp. 127, 131), 

 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 in an adult, 

 this being repeated on subsequent days. Some of the spinal fluid 

 is removed and then the serum is injected, undue pressure being 

 avoided. 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. The most favourable effects have been observed 

 in children of from 2 to 5 years of age. 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 opsonins, ag- 

 glutinins, immune-bodies which bind complement, and possibly 

 also anti-endotoxins. After the injection the number of meningo- 

 cocci 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 



