240 RELATIONSHIPS OF THE COCCACE^ 



Second, only two of the twenty-five strains showed a posi- 

 tive Gram reaction on both trials; seven were variable and 

 sixteen consistently negative. This is a much lower pro- 

 portion of Gram stains than that found in any other group. 

 Third, the reduction of nitrates was much more common 

 among the red cocci than in other genera; and the nature 

 of the reduction was characteristic. Fifteen of our 

 twenty-five strains reduced nitrates, and in every case 

 nitrites were formed but no ammonia. Fourth, liquefac- 

 tion of gelatin was rare among the red cocci, and the 

 action was very slow when exerted at all. Only three 

 of our twenty-five strains acted on gelatin in two weeks, 

 and the average depth of liquefaction for these three was 

 only .7 centimeter. 



In these four characters the red chromogens differ 

 from all groups previously considered. In a uniform 

 abundant growth, generally equal at 20 degrees and 37 

 degrees, and in low fermentative power, they resemble 

 the micrococci and sarcinae. The average reaction of 

 our twenty-five strains was slightly acid in dextrose broth 

 (.003 normal) and neutral in lactose broth. Only four 

 strains formed over .004 normal acid in dextrose broth 

 and only two over .001 normal acid in lactose broth. 

 Finally, in the relation of chromogenesis to temperature 

 the red cocci resemble the aurococci rather than the sap- 

 rophytic forms. Twenty-one of the twenty-five strains 

 showed better pigment production at 20 degrees than at 

 37 degrees. 



