332 APPLICATION OF METHODS OF BACTERIOLOGY 



as may be seen upon cover-slips and in cultures 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, sec- 

 tions 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 

 minute aggregations of small cells, the nuclei of which stain 

 intensely. Almost always evidences of progressing necrosis 

 can be seen about the centre of these cell-accumulations. 



