FAMlL,Y LAClOBACTil^KlACEAJlJ 313 



harmony with the suggestions made b}^ Hucker (Proc. 2nd Internat. Cong, for Micro- 

 biology, London, 1936, 127) and Sherman (Bact. Reviews, 1, 1937, 3). 



Serological reactions are included as far as possible in the descriptions but the true 

 significance of these methods is not known and on that account they are not stressed in 

 the primary classification. 



Throughout the history of this genus motile streptococci have been reported oc- 

 casionally (e.g., Streptococcus herbarum Schieblich, Cent. f. Bakt., I Abt., Orig., 134, 

 1932, 269; Koblmuller, Cent. f. Bakt., I Abt., Orig., 133, 1934, 310; Stolting, Uber die 

 Streptokokken des normal reifenden Tilsiter Kases. Inaug. Diss., Kiel, 1935, 51; 

 Pownall, Brit. Jour. Exp. Path., 16, 1935, 155) but it is not known whether these con- 

 stitute definite species or whether (Leveison, Ann. Inst. Past., 60, 1938, 93) motile in- 

 dividuals occasionally appear in ordinarily non-motile species. 



The anaerobic streptococci have not been sufficiently studied to be sure whether 

 they should be included in the genus Streptococcus or given separate generic rank. 

 Their metabolic processes seem reason for the latter view. The descriptions given 

 are taken from Prevot (Ann. Sci. Nat., Ser. Bot., 15, 1933, 23). 



The material is arranged accordingly in three categories : A key and complete de- 

 scriptions have been prepared for clearly defined species, species of uncertain taxo- 

 nomic relationships have been placed in Appendix I with their necessarily incomplete 

 descriptions, while even less valid and unidentifiable species are merely listed in 

 Appendix II. 



Key to the species of genus Streptococcus. 



I. Facultative anaerobic species. 



A. Pyogenic group. No growth at 10°C. No growth at 45° C. Generally 



beta hemolytic. Generalh^ do not curdle litmus milk and reduce lit- 

 mus slowly if at all. Mannitol and glycerol generally not fermented. 

 Not tolerant of 0.1 per cent methylene blue, 6.5 per cent NaCl and pH 

 9.6. Produce ammonia from peptone. 



1. Sodium hippurate not hydrolyzed. 



a. Lactose fermented. 



b. Sorbitol not fermented but trehalose fermented. Lancefield 

 Group A. 



1. Streptococcus pyogenes. 



bb. Sorbitol fermented and trehalose not fermented. Lancefield 

 Group C. 



2. Streptococcus zooepidemicus . 



aa. Lactose may or may not be fermented. Lancefield Group C. 

 b. Trehalose not fermented. 



3. Streptococcus equi. 

 bb. Trehalose fermented. 



4. Streptococcus equisimilis. 



2. Sodium hippurate hydrolyzed. Lancefield Group B. 



5. Streptococcus agalactiae. 



B. Viridans group. No growth at 10°C. Growth at 45°C (few exceptions in 



Streptococcus mitis). Reduce litmus after curdling litmus milk ; sorbitol 

 and glycerol generally not fermented; mannitol rarely. Not tolerant of 

 0.1 per cent methylene blue, 6.5 per cent NaCl or pH 9.6. Not beta 



