76 IMMUNITY 



there are in this country four groups of pneumococci in a serolog- 

 ical sense, a discovery confirmed by therapeutic results. It is 

 possible to prepare curative anti-sera against two of the groups 

 while the other two fail to call forth useful anti-bodies. In any 

 given case of pneumonia the type of infecting organism is deter- 

 mined by isolating it from the sputum and performing the agglu- 

 tination test with the individual sera of Types I and II, whereupon 

 should one of these react the appropriate anti-serum can be in- 

 jected. The organisms are obtained for the agglutination test 

 by injecting the sputum into a mouse's peritoneum, killing the 

 animal after six to eight hours and using the rich growth of cocci 

 in the peritoneal fluid as the bacterial suspension. With Type I 

 the therapeutic results are very promising; with II helpful at times. 

 Type III is the Pneumococcus mucosus yielding no useful anti- 

 serum, while Type IV is a heterogeneous group possessing no 

 serological uniformity and unable to call forth any valuable anti- 

 body in the injected horse. The serum is given intravenously in 

 dose of 50-100 c.c. and repeated when the temperature rises 

 again, sometimes every eight hours. 



Meningitis Anti-serum. Epidemic meningitis, caused by the 

 Micrococcus meningitidis intracellularis or meningococcus, can 

 be treated by anti-serum. The cocci owe their power to endo- 

 toxins and pus formation, exerted chiefly in the coverings of the 

 central nervous system. They are present in the spinal fluid, 

 only being found in the blood early in an ordinary attack or 

 in highly septicemic cases. Anti-serum is made by injecting 

 horses with first dead then living bacteria until its serum shall 

 have acquired high agglutinative, opsonic and bactericidal 

 power. The horse's serum is separated, preserved as usual, and - 

 used by injecting into the arachnoid space by lumbar or cranial 

 puncture. This route is selected to bring the anti-serum into 

 close relation with the cocci since by the subcutaneous or intra- * 

 venous routes insufficient anti-bodies pass from the blood to the 

 meningeal fluid. It should be given also into the blood stream 



