Ill] HUMAN BLOOD CORPUSCLES. COUNTING 23 



The film should be examined (h. p.) dry, after staining and 

 before mounting ; if the staining is too faint, it should be placed 

 for a few seconds in the eosin or methylene blue ; if the stain is 

 too deep, it should be placed for a second in 75 p.c. alcohol. 



Observe in the film stained with eosin and methy- 

 lene blue the following forms of white corpuscles. 



a. The finely granular cells (polynuclear cor- 

 puscles) ; they are larger than the red corpuscles, they 

 have rather deeply stained irregular or fragmented 

 nuclei ; their cell-substance has small eosin stained 

 granules. Ordinarily, about 75 p.c. of the white cor- 

 puscles are of this kind. 



b. The large mononuclear cells; they also are 

 larger than the red, the cell-substance has a faint blue 

 stain without distinct granules, the nucleus is round 

 and is not deeply stained. 



G. The small mononuclear cells (lymphocytes); 

 these are about the same size as the red, the cell- 

 substance stained a faint blue is small in amount, the 

 nucleus is round and deeply stained. 



d. The coarsely granular cells, crowded with 

 granules stained deep red, and crescent-shaped nucleus, 

 stained less deeply than those of the polynuclear cells. 

 Probably one or two only will be seen. 



When these corpuscles are obtained in their spherical form, 

 the granules are less striking than when they are flattened. If 

 the blood is exposed for a short time before the film is made, 

 the coarsely granular cells may be the only ones obtained 

 separately, such other colourless cells as have not disintegrated 

 being present in clumps. 



