THE GENUS SARCINA 227 



upon gelatin, the red chromogens, whether they occur 

 in packets or not, form a distinct group of their own. 

 We have, therefore, separated the red packet formers 

 from the genus Sarcina and have referred them to the 

 genus RJwdococcus. 



With the elimination of these organisms, the genus Sar- 

 cina includes a series of saprophytic cocci producing a vig- 

 orous yellow (or whitish) growth on agar and exerting only 

 a slight action on carbohydrate media. In our own series 

 of cultures we have studied one hundred and thirty-seven 

 strains of this general type. They form a compact group 

 and one strikingly parallel to that of the micrococci. How 

 close this parallelism is, has been pointed out in Chapter IV. 

 It need only be recalled here that, in relation to the Gram 

 stain, in action on dextrose and lactose broth, in the effect 

 of temperature on chromogenesis, in the shade of color 

 produced, and in gelatin liquefaction, the quantitative 

 characters of the two genera were the same. The sur- 

 face growth of the sarcinae was heavier than in the 

 case of the micrococci, as might naturally be expected. 

 The growth of the sarcinae was also better at 20 degrees in 

 a larger proportion of cases. Their liquefying action was 

 a little stronger. With these exceptions, and the occur- 

 rence of the packet groupings, the two series are alike. 



It will be seen in succeeding pages that the specific types 

 included in the two genera are identical, both in characters 

 and in numerical frequency. In view of all these evidences 

 of likeness between the packet-forming and non-packet- 



