POLYHEDRAL CELLS. 49 



immediately transferred to a slide and covered. To provide against 

 evaporation, run a drop of sweet oil around the edge of the cover. 



FIG. 33. HUMAN BLOOD PRESERVED WITH OSMIC ACID. 



A. Colored corpuscles. 



B. Colorless corpuscle. 



C. C, C. Groups of plaques. X 400 and reduced. 



The blood-plates may be found, after careful search, bearing the 

 relation to the red corpuscles seen in Fig. 33. 



WHITE OE COLORLESS BLOOD-CORPUSCLES. 



The white blood-corpuscle is a typical cell, spherical in form, 

 presenting generally a nucleus often two or more with nucleolL 

 In diameter about the one-twenty-five hundredth of an inch, they are 

 usually found in the blood in proportion of one to three hundred to one 

 thousand red corpuscles. The nucleus of the white corpuscle possesses 

 nearly the same refractive index as the body of the cell, and is there- 

 fore difficult of demonstration without the use of reagents or staining. 



Procure a drop of pus from a healing wound, mix it on a slide with 

 an equal quantity of dilute eosin solution, cover and examine H. 



Pus is colorless, containing spherical nucleated corpuscles, the 

 perfect ones resembling exactly those found in healthy blood. Ob- 

 serve that the nuclei, some cells containing three or even four, are 

 stained with the eosin. Minute pigment granules and fat globules 

 appear in many of the pus cells, and others are broken and distorted. 



POLYHEDRAL CELLS. 



With a scalpel scrape the cut surface of a piece of liver from a 

 recently killed pig ; place a minute portion of the finer part on a 



