STANDARD METHODS AND REAGENTS 469 



2. Hydrolysis. 



Sections are exposed for two minutes to the action of cold dilute hydro- 

 chloric acid, followed by digestion for four to fifteen minutes in the same 

 strength of acid at a temperature of 60° C. 



Hydrochloric acid s.g. 1.19 82.5 c.c. 



Distilled water 1000.0 c.c. 



3. Rinse in cold dilute hydrochloric acid. 



4. Rinse in distilled water. 



5. Stain in fuchsin-sulphurous acid ninety seconds. 



Basic fuchsin i gm. 



Distilled water 200 c.c. 



Boil, cool to 50° C, filter, add 20 c.c. of the dilute hydrochloric acid. When 

 further cooled to 25° C, add i gm. of anhydrous sodium sulphite. When 

 the solution is decolorized it is ready for use and should be kept in the dark. 



6. Pass through 3 baths of dilute sulphurous acid. 



Distilled water 200 c.c. 



10 per cent aq. sol. of sodium sulphite 10 c.c. 



Dilute hydrochloric acid 10 c.c. 



7. Rinse in distilled water. 



8. Counterstain in light green. 



9. Mount in damar. 



To make permanent preparations of hemaflagellates, smears of 

 blood or tissue are made as follows : 



A clean slide is laid upon a flat surface ; a drop of blood is placed 

 near one end and another slide (the spreader) is held between 

 the thumb and middle finger at an angle of about 30° and is 

 brought back until the blood is touched with the spreader and is 

 distributed along its edge. The spreader is now pushed to the op- 

 posite end of the first slide so that the drop of blood is distributed 

 evenly along the surface of the slide. Smears of tissue such as 

 liver or spleen are made by lightly dabbing the slide with the cut 

 surface of the tissue. Smears of blood or of tissue may be allowed 

 to dry, after which they may be stained with Wright's, Leishman's 

 or other modifications of Romanowsky stains, with the exception 

 of Giemsa, in w^hich case they should be previously fixed with 

 absolute methyl alcohol. 



In using Wright's, Leishman's, Wilson's, Hasting's or any of 

 these similar preparations which are dissolved in a fixative (ab- 

 solute methyl alcohol) the film is covered with the stock stain 

 for from forty-five seconds to two minutes, after which distilled 



