THE GENUS AUROCOCCUS 183 



power in different carbohydrates, would no doubt lead to 

 the identification of other specific centers. 



The largest number of our strains grouped themselves 

 about a center, of which the organism commonly known 

 as the Staphylococcus pyogenes aureus, Aurococcus aureus, 

 according to our terminology, may be taken as a type. 

 This form shows strong acid production and rapid lique- 

 faction of gelatin but fails fo reduce nitrates. The Auro- 

 coccus of this type produces an acidity of about .005 

 normal in either dextrose or lactose broth, after fourteen 

 days at 20 degrees, and liquefies gelatin in a tube of 1 cm. 

 diameter to a depth of 2.5 cm. in thirty days at 20 degrees 

 (Winslow and Rogers, 1906). Of the one hundred and 

 eighty cultures of aurococci studied, ninety-six fell in this 

 group. Some strains were of course weaker, and some 

 stronger, than the normal in acid production and gelatin 

 liquefaction. On the whole, however, the group was a 

 fairly homogeneous one. Eighty-one out of the ninety- 

 six cultures were isolated from the human or animal body, 

 either from pathological lesions or from the normal skin. 

 The Gram stain was generally positive, only one cul- 

 ture showing two successive negative results. Most of 

 the cultures grew equally well at 20 and 37 degrees 

 (eighteen growing better at 37 degrees), but seventy-two 

 of the ninety-six showed better color production at 20 

 degrees. 



This type is evidently the Staphylococcus pyogenes, var. 

 aureus, of Rosenbach, the M. pyogenes of Lehmann and 



