MICROCOCCUS INTRACELLULARIS MENINGITIDIS 521 



A special study of the resistance of meningococci to various 

 dye stuffs has been made by Binger. 16 An interesting result of 

 these investigations was that Binger found that methylene-blue 

 had a specific inhibiting action upon meningococcus and gonococcus 

 at dilutions too IOAV to inhibit other pathogenic microorganisms, and 

 that this inhibitory action was not interfered with by the presence 

 of the protein in spinal fluid or other exudates. 



Toxic Products of the Meningococcus. No soluble exotoxin has ever 

 been conclusively isolated from meningococcus cultures. A substance 

 which causes acute symptoms in rabbits within an hour can be recovered 

 from young broth cultures of meningococci, and from filtered wash- 

 ings from meningococcus cultures on agar. These substances are 

 analogous to the so-called "X" substances which one of the writers 

 with Kuttner and Parker 17 has described, which are non-specific, can 

 be obtained from many different microorganisms and are non- 

 antigenic. That they are a very real and important substance in 

 connection with meningococci we are persuaded to believe by the fact 

 that those who immunize horses for serum production with meningo- 

 cocci find that it is necessary to wash the agar cultures once before 

 injecting into horses, otherwise severe symptoms occasionally result. 



A number of investigators have found that cultures that have been 

 kept in broth long enough for a certain amount of extraction or 

 autolysis to occur, yield toxic products which are in general identical 

 in their action to that of whole meningococci injected in analogous 

 quantities. This has been the experience of Flexner, 18 Kraus and 

 Doerr, 19 and others. Extracts of meningococci made with salt solution, 

 weak sodium hydrate, etc., kill guinea pigs within 24 hours, with 

 symptoms of general intoxication, peritoneal exudates, and often 

 pleural exudates. Intravenous injection of sufficient quantities of such 

 extracts or of dead meningococci may kill rabbits. No reliable or con- 

 stant results with such substances have been obtained, but it is quite 

 definite that the bodies of meningococci, like the bodies of typhoid and 

 colon bacilli, are toxic for animals by what is generally spoken of as an 

 endotoxin action. 



16 Binger, Jour. Infec. Dis., 25, 1919, 277. 



17 Zinsser, Kuttner and Parker, Proc. Soc. Exper. Biol. and Med., November, 

 1920. 



18 Flexner, Cent, f . Bakt., 43, 1907. 



19 Kraus and Doerr, Wien. klin. Woch., 1908. 



