60 CIRCULATORY SYSTEM. 



Effect of acetic acid. The red cells are cleared up and the 

 white ones come prominently into view. The latter are 

 rendered transparent and their nuclei distinctly visible. Note 

 the shapes of the nuclei. 



Ppeparations of fixed blood. Dried blood film. A cover is 

 moistened with blood, a second cover is laid upon it, after a minute 

 the two are slid apart and are rapidly dried in air. Invert upon 

 a slide and fasten down with a piece of gummed label having an 

 aperture cut in the centre. 



The red cells are perfectly preserved and visible but the 

 leucocytes are more difficult of recognition. 



Stained films. A successful result depends upon the thinness 

 <>f the film. 



L Make several blood films by rapidly drawing the edge 

 of a square cover moistened with blood across the surface of 

 other covers. 



2. Dry them quickly by waving in the air. 



3. When perfectly dry pass the covers, film uppermost, three 

 times through the flame of the Bunsen burner. 



4. Stain them for 10 seconds in a quarter saturated alco- 

 holic solution of eosin. The stain is applied by spreading a 

 drop of the fluid at one stroke over the film with the flat of 

 the rod of the reagent bottle. 



5. Rinse in successive drops of water until the stain ceases 

 to discharge. 



6. Stain in the same manner for 30 seconds in Loffler's 

 methelyne blue. 



7. Rinse as before in water. 



8. Blot off the moisture by placing the cover between the 

 folds of a piece of filter paper. 



