142 NORMAL HISTOLOGY. 



hoi. They are stained double and mounted in balsam. 

 b. Human. Structural details may be studied in a sec- 

 tion from a human spleen hardened as above. Before 

 mounting, the sections should be placed in a shallow, 

 flat-bottomed dish, and just covered with water ; with a 

 fine camel's hair pencil, held perpendicularly, the section 

 is gently tapped until it appears thinner and more trans- 

 parent from the brushing out of the loose cells. It may 

 then be stained double, and mounted in glycerin or 

 balsam. 



Section of Spleen with Injected Cavernous Veins. A 

 spleen is injected, under low pressure, through the vein, 

 with the blue gelatin mixture, hardened in alcohol, 

 stained deeply with eosin, and mounted in balsam. 



Isolated Cells of the Spleen. A freshly cut surface of 

 the human spleen is gently scraped with a scalpel and 

 the scrapings diffused in a large quantity of Mtiller's 

 fluid. After twenty-four hours the Miiller's fluid is de- 

 canted, the sediment washed well with water, and then 

 further hardened in eighty-per-cent. alcohol. They are 

 then stained with.picro-carmine and mounted in glycerin. 

 In addition to the above-described cells of the pulp- 

 comb, narrow, elongated, often curved cells, with pro- 

 jecting nuclei, are frequently seen ; these are the 

 above-described lining cells of the cavernous veins. 



