208 



MICROBIOLOGY 



lently adapted for the demonstration of these organisms in 

 sections of tissue. 



Cultivation. This organism grows readily on the usual 

 laboratory media. The optimum temperature for its growth 

 is about 35 C. although it develops at temperatures as low as 

 15 C. and as high as 40 C. It is an ae'robe and facultative 

 anaerobe. It grows readily in an atmosphere of hydrogen. 



Micrococcus pyogenes develops most favorably upon 

 media having a slightly alkaline reaction. Moderately in- 

 creased alkalinity or acidity of the media does not inhibit 

 growth. 



Fig. 48. Micrococcus pyogenes aureus. Drawing from a cover-glass 

 preparation of a bouillon culture. Highly magnified. 



Agar. On slant agar'the growth is rapid and moderately 

 fleshy. At first it is of a grayish-white, but later develops a 

 glistening golden yellow color. 



Gelatin. On gelatin plates, growth occurs readily at room 

 temperature. Within 36 to 48 hours, small, shining, pin-head 

 shaped colonies appear, at first grayish-white, and later as- 

 suming a yellowish hue, which intensifies into a light brown 



