THE GENUS DIPLOCOCCUS 125 



have found races of the meningococcus which showed 

 short chains, at times, which stained by Gram, and 

 grew at 20 degrees; while Weichselbaum (1902), and his 

 associates at Vienna (Albrecht and Ghon, 1902), stoutly 

 maintained that the true D. Weichselbaumii never formed 

 chains of more than four elements, never stained by Gram, 

 and never grew at 20 degrees. 



Jaeger (1903) reported that meningococci of both types 

 exhibited specific agglutination reactions in immunized 

 rabbit's blood, while slightly different organisms, and 

 those derived from other sources than meningitis, were 

 differently affected. D. catarrhalis was agglutinated by 

 physiological salt solution! 



Libman (1902) isolated only the typical form of 

 D. Weichselbaumii from the New York cases studied 

 by him, and was inclined to discredit the findings of 

 the Jaeger school. The evidence for the existence of 

 atypical meningococci is, however, too considerable to 

 be lightly put aside. Lepierre (1904) studied D. Weich- 

 selbaumii with considerable care and came to the con- 

 clusion that this species, like others, exhibits widely vary- 

 ing races. As obtained from the spinal fluid, the organism 

 appeared only in characteristic pairs of flattened cells; 

 but on cultivation in ascites-bouillon, chains appeared more 

 and more frequently in successive generations. The 

 ability to grow on artificial media rapidly increased during 

 the same process. After this development of vigor by 

 artificial cultivation the organisms were capable, in large 



