THE GENUS ALBOCOCCUS 195 



distinguished, differing in hemolytic power and in re- 

 sponse to agglutinating sera. The pathogenic form is the 

 Staphylococcus pyogenes albus (or Micrococcus pyogenes) ; 

 the other is probably the one described under the name 

 Staphylococcus epidermidis albus. Until these data with 

 regard to immune reactions are correlated with observa- 

 tions of other biological characters, it is impossible accu- 

 rately to define the avirulent type. 



The most important contribution to the comparative 

 biology of this genus has been made by Gordon, who 

 extended his studies on the fermentative powers of the 

 streptococci to the " staphylococci," and mainly to the 

 white forms. These organisms were found (Gordon, 

 1905) to differ from the streptococci in producing acid 

 somewhat more slowly, in reducing nitrates, in failing to 

 ferment the glucosides, salicin and coniferin, in liquefying 

 gelatin, and in other less sharply marked reactions. Nine 

 tests were selected, as being of most value for the dif- 

 ferentiation of the white staphylococci, including lique- 

 faction of gelatin, coagulation of milk, reduction of neutral 

 red, and the fermentation of lactose, maltose, glycerin, and 

 mannite. Forty-one strains were examined by these tests, 

 and the commonest type was found to be the one which 

 liquefied gelatin, reduced nitrates, and fermented maltose 

 and glycerin, but failed in the other five reactions. In the 

 next year Gordon (1906) examined over three hundred 

 strains of staphylococci. All, without exception, showed 

 a positive reaction to the Gram stain, altho seven cultures 



