THE GENUS STREPTOCOCCUS I$7 



brevis) and in the tendency to form coherent growths in 

 broth (Str. conglomeratus). Of seventy-seven cultures, 

 sixty coagulated milk and twelve more produced acid in 

 it. All fermented dextrose. Neutral red, however, was 

 reduced only by organisms of the Str. brevis type, and 

 this appeared to offer a valuable means of differentiation. 

 Of twenty-two cultures isolated from the air, six resembled 

 the common mouth-type (Str. brevis), but the other 

 sixteen differed in failing to reduce neutral red. In an 

 addendum to this paper, Gordon noted that experiments 

 with twelve cultures, in regard to their acid production 

 in various sugars, indicated that all fermented dextrose, 

 levulose, maltose, and galactose, and none altered dulcitose 

 or starch. Lactose, saccharose, inulin, raffmose, and 

 mannite, on the other hand, were acted upon by some 

 strains and not by others, and their use for diagnostic pur- 

 poses seemed promising. 



In the next year Gordon (1905) worked out the fermen- 

 tative powers of the group in a more comprehensive manner. 

 He first noted the effect of ten different cultures of strep- 

 tococci upon thirty-five different organic compounds. 

 Many of these substances were affected by all ten strains, 

 and others by none of them. The details, which are full 

 of suggestiveness in relation to the biology of these bac- 

 teria, are given in the original paper. Seven carbohy- 

 drates were finally selected as of special differential 

 value, being acted upon by some strains but not by others. 

 They included two disaccharides, saccharose and lactose; 



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