900 



PROTOZOOLOGY 



thoroughly dry, immerse the thick film part in distilled water and de- 

 haemoglobinize it. Let the slide dry. 



Blood smears must be stained as soon as possible to insure a proper 

 staining, as lapse of time or summer heat will often cause poor stain- 

 ing especially of thick films. Of several blood stains, Giemsa's and 

 Wright's stains are used here. For staining with Giemsa's stain, the 

 thin film is fixed in absolute methyl alcohol for 5 minutes. Rinse well 



Fig. 376. Diagrams showing how a thin blood film is made on a slide. 



the slide in neutral distilled water. After shaking the stock bottle 

 (obtained from reliable makers) well, dilute it with neutral distilled 

 water in a ratio of one drop of stain to 1-2 cc. of water. Mix the solu- 

 tion and the blood film is placed in it for 0.5-2 hours or longer if 

 needed. Rinse the slide thoroughly in neutral distilled water and 

 wipe off water with a tissue paper from the underside and edges 

 of the slide. Let the slide stand on end to dry. When thoroughly dry, 

 place a drop of xylol and a drop of cedar wood oil (used for immersion 

 objectives) and cover with a coverglass. The mounting medium 



