MICROCOCCUS AUREVS. 271 



These minute abscesses have a dry, cheesy, necrotic 

 centre, in which the micrococci are present in large 

 numbers, as may be seen upon cover-slips and in cul- 

 tures prepared for them. 



Preserve in alcohol bits of all tissues in which the 

 abscesses are located. When these tissues are hard 

 enough to cut, sections should be made through the 

 abscess-points and the histological changes carefully 

 studied. 



MICROSCOPIC STUDY OF COVER-SLIPS AND SECTIONS. 

 In cover-slip preparations this organism stains readily 

 with the ordinary dyes. In tissues, however, it is best 

 to employ some method by means of which contrast- 

 stains may be utilized, and the location and grouping of 

 the organisms in the tissues rendered more conspicuous. 

 When stained, sections of tissues containing the small 

 abscesses present the following appearances : 



To the naked eye will be seen here and there in the 

 section, if the abscesses are very numerous, small, darkly 

 stained areas which range in size from that of a pin- 

 point up to those having a diameter of from 1 to 2 mm. 

 These points, when in the kidney, may be round or oval 

 in outline ; or may appear wedge-shaped, with the base 

 of the wedge toward the surface of the organ. The 

 differences in shape depend frequently upon the direction 

 in which the section has been made through the kidney. 

 In the muscles they are irregularly round or oval. 



When quite small they appear, in stained sections, to 

 the naked eye, as simple, round or oval, darkly stained 

 points ; but when they are in a more advanced stage a 

 pale centre can usually be made out. 



When magnified they appear in the earliest stages as 



