626 DIPLOCOCCUS CRASSUS 



error (Chap. XII.).' It is well to cauterize a small area of the surface through which 

 to pass the needle or pipette for the collection of the material. 



(c) Inoculations. To ascertain the virulence of cultures, rabbits should 

 be inoculated both sub-cutaneously and also intra-venously into the ear 

 vein. . 



Diplococcus crassus. 



The organism isolated by Jaeger from cases of cerebro-spinal meningitis and 

 identified by Jaeger and Huebner with the Meningococcus (Chap. XL VII.) is clearly 

 a different organism from the latter and is identical with the Diplococcus crassus. 

 It is a saprophyte inhabiting the pharynx but may be found in association with the 

 Meningococcus and even with the tubercle bacillus in cases of meningitis. It differs 

 mainly from the Meningococcus in the following particulars : 



1. Staining reactions. The Diplococcus crassus is gram-positive. 



2. Cultures. It grows on ordinary media at 20 C. and above. 



3. Fermentation reactions. It ferments nearly all the sugars notably Isevulose, 

 galactose, lactose and saccharose on all of which the Meningococcus has no action. 



4. Agglutination. The Diplococcus crassus is not, as a rule, agglutinated by an 

 antimeningococcal serum : occasionally however agglutination is noticed with 

 dilutions of 1 in 25 and 1 in 50. But this ( is a group-agglutination similar tojthat 

 which occurs with the Gonococcus and referred to later (Chap. XLVIL). 



An anticrassus serum has no agglutinating action on the Meningococcus (Wasser- 

 mann). 



The organism described by Lepierre as a Meningococcus exhibits all the charac- 

 teristics of the Jaeger- Huebner coccus and is apparently identical with that organism : 

 Lepierre found that the virulence was increased by passage through the peritoneal 

 cavities of rabbits. 



