162 RELATIONSHIPS OF THE COCCACE^E 



(salicin and coniferin), but not lactose, rajfinose, inulin, or 

 mannite. It fails to clot milk or to reduce neutral red. 



2. Streptococcus mitis (Andrewes and Horder). 

 This type is found most commonly in human saliva and 



faces, but is not as a rule associated with disease. It is 

 short-chained, grows well on gelatin at 20 degrees, and 

 acidifies milk without clotting. It ferments lactose as well 

 as saccharose and salicin, but gives a negative reaction to 

 the other tests. 



3. Streptococcus pyogenes (Andrewes and Horder). 

 This type represents the highest parasitic develop- 

 ment of the group, being rarely found except in associ- 

 ation with definite pathological conditions. It occurs 

 in long chains, usually growing in woolly masses at the 

 bottom of a clear broth. It grows well on gelatin at 

 20 degrees. It is actively hemolytic, but does not form 

 hydrogen sulphid in broth culture. It strongly acidifies 

 milk, but never clots it, nor does it reduce neutral red. 

 The usual positive reactions with Gordon's tests are 

 saccharose, lactose, and salicin. It is highly pathogenic 

 for animals. 



4. Streptococcus salivarius (Andrewes and 

 Horder). This type is the commonest form in the mouth, 

 altho it is also found in the intestine. It is a short- 

 chained form- which usually renders broth uniformly tur- 

 bid. Its growth on gelatin at 20 degrees is variable. It 

 clots milk and reduces neutral red and ferments saccharose, 

 lactose, and raffinose. 



