Generic Characters in the Coccaceae 



203 



Of our cultures 262 fall under this head, 195 of them coming 

 from water, earth, or air, and only 64 from the body; 200 are uni- 

 formly or at times Gram negative, and only 62 uniformly Gram pos- 

 itive. The average acidity produced in dextrose broth is only 

 0.2 per cent normal, and in lactose broth o.i per cent normal. 

 Of the 262 cultures only t,t, give over o . 5 per cent acid in dextrose 

 broth, and only 7 over o . 5 per cent acid in lactose broth ; 59 of the 

 cultures reduce nitrates; 85 fail to act on gelatin, and 177 liquefy it, 

 producing an average liquefaction of 1.2 cm., scarcely more than 

 half the value in the genus Aurococcus. 



This group divides itself, according to cell-grouping, into two 

 nearly equal divisions — those which form packets and those which 

 do not; 136 belong to the former class, and 126 to the latter. In 

 habitat, in Gram staining, and in relation to carbohydrates and 

 gelatin both classes are entirely parallel. The genera Micrococcus 

 and Sarcina are, however, so firmly established in common usage 

 that it would require very strong evidence of identity to warrant 

 dropping either of them. It seems best, therefore, to recognize 

 the single character of cell-grouping as having generic value in this 

 case, otherwise defining the two genera by the same characteristics. 

 Under Micrococcus will come M. orbicularis Ravenel, M. luteus 

 (Schroter) Cohn, and M. ochraceus Rosenthal; under Sarcina, St. 

 subflava Ravenel and S. venlriculi Goodsir. 



The fifth and last of our general types includes the sharply marked 

 one of the red chromogens. These are entirely saprophytic forms 

 which produce abundant surface growths of a red color. They 

 may or may not show packets, are generally Gram negative, very 

 rarely liquefy gelatin or ferment carbohydrates, and frequently 

 reduce nitrates to nitrites, but apparently not to ammonia. This 

 is the first case in which we have found the action upon nitrates 

 markedly correlated with other characters. 



Twenty-five of our cultures fall under this general type. All 

 but one come from earth, water, or air. Only three are uniformly 

 positive to Gram, while 15 are uniformly negative. Four of the 25 

 cultures liquefy gelatin, and 14 reduce nitrates to nitrites. The 

 average acidity in dextrose broth is 0.4 per cent normal, and in 

 lactose the average reaction is neutral. One culture in lactose 

 and four in dextrose show an acidity over 0.5 per cent. 



