198 



OPSONIC INDEX 



with a saturated solution of mercuric chlorid or with pure methyl 

 alcohol for two minutes. Wash in water and dry. 



2. Heat a portion of carbolfuchsin almost to boiling in a test-tube, 

 and pour the hot stain over the films. Allow to remain for at least 

 fifteen minutes. Wash under the tap and dry. 



FIG. 50. METHOD OF SEALING A CAPILLARY PIPET. 



The tip of the pipet is placed in the edge of a flame. The teat is held in the 

 same position until the tip has been sealed, when it may be removed without disturb- 

 ing the contents of the pipet. 



3. Cover with a 5 per cent, solution of nitric or sulphuric acid for 

 half a minute or longer if necessary, until decolorization is complete. 

 Wash thoroughly under the tap. 



FIG. 51. METHOD OF PREPARING A BLOOD FILM. 



The slide is laid on a flat surface; the drop of blood is placed near one end; the 

 spreader is held between the thumb and middle finger of the left hand, at an angle of 

 about 30 degrees, and quickly pushed to the opposite end of the slide. 



4. Cover with 4 per cent, aqueous solution of acetic acid for one to 

 two minutes to remove the hemoglobin from the red cells. Wash and 

 blot lightly. 



5. Cover with Loffler's methylene-blue for two minutes. Wash in 

 water and dry thoroughly (Fig. 53). 



