Pathogenesis 391 



and by quite moderate variations of temperature. It succumbs to 

 very high dilutions of most germicides in a very short time. 



The thermal endurance of the organism is very slight. It will 

 not grow except at 37°C., ceases to grow at 4o°C. It is killed in 

 five minutes at 6o°C. 



Agglutination. — When animals are immunized by repeated 

 injections of the Diplococcus intracellularis, their blood-serum 

 and body-juices become agglutinative. Such serums kept in the 

 laboratory can be used for the identification of the coccus in fresh 

 culture, though the reaction is not exact, since the agglutinability 

 of different strains of cocci is different. The serums have an ag- 

 glutinating power that varies from i : 500 to i : 3000 in the hands of 

 different observers. 



Metabolic Products. — The meningococcus breaks up dextrose and 

 maltose with the production of acids, but has no similar action upon 

 levulose, saccharose, or inulin. Acid production is unaccompanied 

 by gas evolution. To determine the acid the coccus may be grown 

 upon acetic-fluid agar containing the sugar under examination, and 

 a little litmus or neutral red. 



No indol is produced, no gelatin-softening coagulating or other 

 ferments are formed. 



The meningococcus prodiices an endotoxin. Albrech and Ghon* 

 were able to kill white mice with dead cultures. Lepierref obtained 

 a toxin from bouillon cultures by precipitating them with alcohol. 



Pathogenesis. — The results of animal inoculations made with 

 Diplococcus intracellularis meningitidis are disappointing. Sub- 

 cutaneous inoculations into the lower animals are continually with- 

 out effect. Intrapleural and intraperitoneal injections of cultures 

 of the organism into mice and guinea-pigs are sometimes fatal, 

 the dead animals showing a serofibrinous inflammation with the 

 presence of the cocci. The intravenous injection of the coccus into 

 rabbits is followed by death without important or conclusive symp- 

 toms, and usually without the presence of cocci in the blood. 



Weichselbaum endeavored to reproduce the original cerebro- 

 spinal meningitis in animals by trephining and injecting the cocci 

 beneath the dura. In this manner he inoculated three rabbits and 

 three dogs. Two of the rabbit injections failed, probably because 

 the injected material escaped at once from the wound. The third 

 rabbit died, and showed marked congestion of the membranes of 

 the brain and a minute softened and hemorrhagic area. In these 

 the cocci were found by culture to be abundant. The three dogs all 

 died with congestion and pus-formation in the membranes and 

 areas of softening in the brain substance. The cocci were recovered 

 from two of the dogs, but the lesions of the third animal, which lived 

 twelve days, contained none. 



* "Wiener klin. Wochenschrift," igoi. 



t "Jour, de phys. et de path, g^n.," v, No. 3. 



