GENERAL SYSTEMATIC BACTERIOLOGY 395 



Myxococcus. A generic name proposed by Thaxter (1892, p. 403) 

 as a genus of the Myxohacteriaceae. The diagnosis given is: "Rods 

 slender, curved, swarming together after a vegetative period to form 

 definite more or less encysted sessile masses of coccus-like spores." 

 In the possession of the coccus-Hke spores when encysted it differs 

 from the other genera of the family, Polyanglum and Chondromyces. 



Eleven species have been described, Myxococcus rubescens Thaxter, 

 M. virescens Thaxter, M. coralloides Thaxter, M. stipitatus Thaxter, 

 M. cirrhosus Thaxter, M. cruentis Thaxter, M. pyriformis A.L.Smith, 

 M. disciformis Thaxter, M. macrosporus Zukal, M. digitatus Quehl, and 

 M. clavatus Quehl. 



The generic name Myxococcus has been accepted and used by Sac- 

 cardo (1899, p. 460) by Zukal (1897, p. 550) and by Quehl (190G, p. 16) . 



With the spelling Myxokokkus this name has been also used inde- 

 pendently by Gonnermann (1907, p. 877) for a species of bacterium 

 M. betae isolated from sugar beet syrup. In this sense the name is 

 invalid. 



Buchanan (1918, p. 542) gave the following description. 



Rods slender, curved, swarming together after a vegetative period to form 

 definite more or less encysted sessile masses of coccus-like spores. 

 The type species is Myxococcus rubescens Thaxter. 



Bergey et al. (1923, p. 413) included this as the first genus of the 

 family Myxohacteriaceae. 



Myxokokkus. A generic name used by Gonnermarm (1907, p. 883) 

 for a species Myxokokkus hetae Gonnermann isolated from a gummy 

 fermentation of sugar beet sap. The organism is a streptococcus. It 

 grows on all ordinary media except potato, but usually not luxuriantly. 

 It forms on dextrose agar no gmn, but only small, at first transparent, 

 discrete colonies with sHght gas formation. On ten per cent sucrose 

 agar and gelatin it produces abundant gum and vigorous gas. The 

 organism quickly dies on this medium. It is possible that in nature 

 development is dependent upon growth with a gum producing bacillus. 

 The genus is probably invahd because of the priority of Mijxococcus 

 Thaxter, and because of the inadequate characterization. Possibly it is 

 a sjTionjTQ of Leuconostoc q.v. 



Neissereae. A tribe of bacteria named by Winslow et al. (1920, p. 

 205) as a tribe of the family Coccaceae. One genus only. Neisseria is 

 included. The diagnosis given is: "Strict parasites, failing to grow 

 or growing very poorly on artificial media. Cells normally in pairs. 

 Gram-negative. Growth fairly abundant on serum media." 



