292 GENERAL SYSTEMATIC BACTERIOLOGY 



use of the name Diplococcus albicans tardissimus, but as this is a trino- 

 mial it is invalid. In the same year Weichselbaum (1886, p. 506) gave 

 to the pneumococcus the name Diplococcus pneumoniae, a valid bino- 

 mial. This seems to be the first correct designation of a species of the 

 genus, and the pneumococcus should therefore be regarded as the type. 

 Several other species were assigned to this genus in the next two years, 

 but of these only four appear to have binomial form and therefore 

 valid. These are Diplococcus roseus and D. subflavus described by 

 Bumm (1887), D. luteus Adametz (1887, p. 9) and D. coryzae Hajek 

 (1888). 



As the designation of a genus, Diplococcus has rarely found its way 

 into formal classifications, although diplococcus is in common use as a 

 casual designation. For example, Sternberg (1892, p. 17) under the 

 heading of Diplococcus makes the following statement: 



Association in pairs is common to all of the micrococci, inasmuch as they multi- 

 ply by binary division. When such association has rather a permanent character 

 it is customary to speak of the microorganism as a diplococcus, but we doubt 

 the propriety of recognizing this mode of association as a generic character. 



Winslow and Rogers (1905, p. 669) have included Diplococcus as 

 one of the valid genera in their studies of the classification of the Coc- 

 caceae. In further contributions on the same subject the genus was 

 accurately defined as follows (1908, p. 250): 



Strict parasites, not growing, or growing very poorly, on artificial media. 

 Cells normally in pairs, surrounded by a capsule. Fermentative powers high, 

 most strains forming acid in dextrose, lactose, saccharose and inulin. Hemolytic 

 power generally lacking. Characteristic group serum reactions. 



They assign to this genus the pneumococcus, the gonococcus, the 

 meningococcus and the coccus of catarrh. 



If the Gram-positive cocci of which the pneumococcus is a type are 

 to be grouped together into a genus, it would appear that the generic 

 name Diplococcus is vaHd; if, however, the gram negative cocci of which 

 the gonococcus is the type are to be included in the same genus, Diplo- 

 coccus becomes a synonym of an earlier genus, Neisseria Trevisan. 

 This latter genus was founded upon the gonococcus by Trevisan in 

 1885 (p. 16). Article 46 of the botanical code states: "When two or 

 more groups of the same natm'e are united, the name of the oldest is 

 retained.-' Inasmuch as the genus Diplococcus as used by the Winslows 

 contains also the type of the genus Neisseria Trevisan, and since the 

 latter name has priority. Neisseria should replace Diplococcus. 



