WHITE AND ORANGE STAPHYLOCOCCI 157 



For simplicity of analysis we have used in the following com- 

 parison only the results obtained in dehydrated broth, which 

 yielded the clearest differentiation between fermenting and non- 

 fermenting forms, and have assumed that in this medium all pH 

 values above 6.0 indicated lack of fermentative power. 



Of the 180 cultures studied 90 or 50 per cent produced a dis- 

 tinct acid reaction (pH 5.9 or below) in all four sugars; 41 or 

 23 per cent produced an acid reaction in glucose, maltose and 

 sucrose but not in lactose; 11 or 6 per cent fermented glucose, 

 maltose and sucrose but not lactose; 11 or 6 per cent fermented 

 glucose and sucrose only; 23 or 13 per cent attacked none of the 

 sugars; while 15 or 8 per cent showed special variations not fitting 

 into either group (glucose-lactose-sucrose, glucose-lactose-maltose, 

 maltose-sucrose, glucose-lactose, lactose-sucrose, glucose alone, 

 sucrose alone, maltose alone). 



In view of the marked variations shown in figure 1 it would 

 seem unsafe to lay stress upon any of the smaller groups indicated 

 by this analysis; and for comparison with other characteristics of 

 the organisms in question we have therefore divided them into 

 three main groups, group I those fermenting all four sugars; 

 group II those fermenting glucose, maltose and sucrose, but not 

 lactose; and group III, including all the rest of the strains. 



Group III is a highly heterogeneous agglomeration; but the 

 forms which fail to ferment lactose (group II) seem to constitute 

 a fairly well defined group. 



Correlations between fermentative power, on the one hand, 

 and habitat, chromogenesis and liquefaction of gelatin, on the 

 other, are indicated in table 5. 



There is a marked tendency for the strains isolated from 

 pathogenic conditions to ferment rather strongly, 76 (73 per 

 cent) of all such strains attacking all four carbohydrates; while 

 of the 54 strains from dust and air only 7 (13 per cent) attacked 

 all four sugars and 30 (56 per cent) belonged to the heterogeneous 

 feebly fermenting, group III. 



Gelatin liquefaction was also slightly but distinctly more com- 

 mon among the active fermenters (60 per cent) while the mem- 

 bers of group III were predominantly non-liquefiers (only 37 

 per cent showing liquefaction). 



THE JOURNAL OF BACTERIOLOGY, VOL. V, NO. 2 



