GENUS MICROCOCCUS 207 



Distribution of micrococci. The micrococci are widely 

 distributed in nature. In certain flora such as that of the 

 cow's udder they are the predominating forms. Ward 1 de- 

 scribes seven micrococci isolated from this flora. Conn, Esten 

 and Stocking 2 describe 22 species in their classification of 

 dairy bacteria. They are present in variable numbers on the 

 mucous membranes of the digestive tract and also on the skin. 

 The pyogenic cocci are numerous about stables and hospitals 

 where suppurating wounds are common. They are frequently 

 found on the hands of those engaged in the dressing of such 

 cases. There is not in general the close resemblance between 

 the micrococci that there is between the streptococci. 



MICROCOCCUS PYOGENES (ROSENBACH) MIGULA. 



Synonyms. Staphylococcus pyogenes aureus Rosenbaeh, 

 grape-coccus, pus coccus. 



Place in nature. This microorganism is one of the most 

 frequent causes of abscesses, wound infection and suppuration. 

 It is quite widely distributed in nature. It has been reported 

 from various external sources, and the skin and mucosae of man 

 and animals. 



Morphology. It is a spherical coccus having an average 

 diameter of about 0.8 /A but varying within the extreme limits 

 of 0.4 to 1.2 p. Any considerable variation from the average 

 size, however, is rare. The perfectly spherical forms do not 

 appear when two or more are grouped together, unseparated 

 after cell division. In this case, adjacent cocci are slightly 

 flattened along their contiguous surfaces. In smears from 

 cultures or pus, it may appear singly, in pairs, or in irregular 

 grape-like clusters. Occasionally, short chains of three or four 

 may be seen. In very young liquid cultures it often appears 

 as a diplococcus. 



Staining. Micrococcus pyogenes stains with all the usual 

 basic dyes, and less intensety, with some of the acid dyes. It 

 stains after Grain's method. This method of staining is excel- 



1 Ward. Bulletin No. 78, Cornell Univ. Exp. Station, 1900. 

 2 Conn, Esten and Stocking. LOG. cit. 



