126 RELATIONSHIPS OF THE COCCACE^E 



doses, of killing rabbits, and a few passages through the 

 animal body produced a considerable degree of virulence. 

 With increasing virulence the relation to the Gram stain 

 also changed. Forms of low virulence generally decolor- 

 ized; but eight or ten passages through rabbits produced a 

 race which was uniformly Gram-positive. The type with 

 which Lepierre started, in each of three separate cases, 

 was the Weichselbaum type of the meningococcus, with no 

 chains, negative Gram reaction, feeble growth on ascites- 

 media, and low virulence. The final result of successive 

 cultivations and animal inoculations was the Jaeger- 

 Heubner type, which stands at the opposite extreme in 

 all these respects. Sorgente (1905), too, has shown that 

 the two types of the meningococcus interchange their 

 characters under varying conditions of cultivation, and 

 that they are not distinguished by specific serum reactions. 



It seems on the whole certain that races of the menin- 

 gococcus may occur which vary from type in viability, 

 staining reactions, and morphology. According to the 

 view of bacterial species which we have been led to adopt 

 this would naturally be the case. The common central 

 type under normal conditions, however, is the one de- 

 scribed by Weichselbaum; and Jaeger's races may be 

 considered as variants about this center. 



3. D. Weichselbaumii (Weichselbaum, Trevisan). 

 A coccus occurring commonly in pairs of flattened coffee- 

 bean shaped cells. Decolorizes by Gram. Develops feebly 

 on ordinary media. Slightly pathogenic for animals. 



