STUDY OF COVER-SLIPS AISTD SECTIONS. 221 



which occupy, as a rule, the area fed by a single vessel. 

 If one makes a section into one of these yellow points it 

 will be seen to extend deep down through the substance 

 of the kidney as a yellow, wedge-shaped mass, the base 

 of the wedge being at the surface of the organ. 



It is very rare that these abscesses — for abscesses tliese 

 yellow points are, as we shall see when we come to study 

 them more closely — are found either in the liver, spleen, 

 or brain ; their usual location being, as said, in the 

 kidney, myocardium, and voluntary muscles. 



These minute abscesses contain a dry, cheesy, necrotic 

 centre, in which the staphylococci are present in large 

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

 them. They may also be obtained in pure culture from 

 these suppurating points. 



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 

 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 employed, 

 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 3 mm. 



