CO VER-SLIPS AND SECTIONS. 249 



These minute abscesses contain a dry, cheesy, necrotic 

 centre, in which the staphylococci are present in lai^e 

 numbers, as may be seen upon cover-slips prepared from 

 them. They may also be obtained in pure culture from 

 these suppurating foci. 



Preserve in Miiller's fluid and in alcohol duplicate 

 bits of all the tissue in which the abscesses are located. 

 When these tissues are hard enough to cut sections 

 should be made through the abscess-points, and the his- 

 tological 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 these 

 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 more advanced a pale centre 

 can usually be made out. 



