526 PATHOGENIC MICROORGANISMS 



solution the volume of all of these tubes is brought up 0.4 c.c. To 

 each of the tubes now 0.4 c.c. of the homologous meningococcus sus- 

 pension is added, giving serum dilutions ranging from 1 to 100, to 1 

 to 800. These are now incubated at 55 for twenty-four hours, as in 

 the first agglutination. The agglutinating titers of the absorbed sera 

 are now compared with those of the un-absorbed, and diminutions of 

 titer are noted. 



Animal Pathogenicity. Animals are not very susceptible to 

 infection with Diplococcus meningitidis. Subcutaneous inoculation 

 is rarely followed by more than a local reaction unless large quan- 

 tities are used. White mice are rather more susceptible than other 

 species. Intraperitoneal and intravenous inoculation of sufficient 

 quantities usually results in the death of mice, rabbits, guinea-pigs, 

 and dogs. Occasional strains have been found to possess a not 

 inconsiderable degree of toxicity for rabbits, grave symptoms or 

 even death following intravenous injection of but moderate quanti- 

 ties without any traceable development of the microorganisms in the 

 organs of the animals. 



Similar observations have been made by Albrecht and Ghon, 33 

 who succeeded in killing white mice with dead cultures. It would 

 seem, therefore, that the effect of this coccus upon animals depends 

 chiefly upon the poisonous substances contained in the bacterial 

 bodies (endotoxins). Lepierre 34 has obtained the meningococcus 

 toxin by alcohol precipitation of broth cultures. 



Weichselbaum himself succeeded in producing meningeal sup- 

 puration and, in one case, brain abscess, by subdural inoculation of 

 dogs. Councilman, Mallory, and Wright produced a disease in many 

 respects similar to the human disease by intraspinous inoculation of 

 a goat. More recently, Flexner 35 has succeeded in producing in 

 monkeys a condition entirely analogous to that occurring in human 

 beings. 



THE DISEASE IN MAN 



The disease produced in man consists anatomically in a suppurative 

 lesion of the meninges, involving the base and cortex of the brain and 

 the surface of the spinal cord. The nature of the exudate may vary 



33 Albrecht nnd Ghon, loc. cit. 



"Lepierre, Jour, de phys. et de path, gen., v, No. 3. 



85 Flexner, Journ. of Exp. Med., 1906. 



