362 



Suppuration 



Staining. The organisms stain well by ordinary methods 

 and beautifully by Gram's method, by which they can be 

 best demonstrated in tissues. 



Isolation. The organism can be isolated by inoculating 

 a white mouse with sputum or pus containing it. After 

 death it can be recovered from the blood. 



Cultivation. It grows readily upon artificial media. 

 Upon gelatin plates small white colonies are produced in 



Fig. 108. Micrococcus tetragenus in spleen of infected mouse. 

 (From Hiss and Zinsser "Text-Book of Bacteriology," D. Appleton & 

 Co., Publishers.) 



from twenty-four to forty-eight hours. Under the micro- 

 scope they appear spheric or elongate (lemon shaped), finely 

 granular, and lobulated like a raspberry or mulberry. When 

 superficial they are white and elevated, i to 2 mm. in diam- 

 eter. 



Gelatin. In gelatin punctures a large white surface 

 growth takes place, but development in the puncture is very 

 scant, the small spheric colonies usually remaining isolated. 

 The gelatin is not liquefied. 



