46 SPOROZOA. 



sections. Fix in Zenker's fluid. Thoroughly wash out the 

 fixative for several hours in gently running water. Stain 

 sections in 0-5 per cent, aqueous solution of acid fuchsin for 



2 to 4 minutes, and transfer to the second solution (consisting 

 of aniline blue soluble in Avater (Griibler) 0-5 grm., orange G 

 (Griibler) 2 grm., 1 per cent, aqueous solution of phosphomo- 

 lybdic acid 100 c.c.) for 10 to 20 minutes or longer. Wash 

 and differentiate the sections in tap-water, dehydrate rapidly, 

 clear, and mount. Lund (1933) recommends Zenker's fluid 

 with 2-5 per cent, acetic acid, staining the sections for 2 minutes 

 in Mallory No. 1 and 1 minute in Mallory No. II, then dipping 

 rapidly into 95 per cent, and absolute alcohol, blotting quickly 

 between each change, and then clearing in xylol for about 



3 minutes. 



Preparation of Dried Films on Slides. — Films of blood, in- 

 testinal contents or other fluids containing parasites are usually 

 made for diagnostic purposes. Films of sohd organs, such 

 as the Kver or the spleen, are made by smearing a piece of the 

 organ hghtly across the shde or dabbing the slide with the 

 freshly-cut surface. The film is dried as rapidly as possible 

 by waving it in the air. Distortion and disintegration of the 

 parasites may take place in the process of making the films 

 and subsequent drying ; to avoid this expose the film to 

 osmic acid vapour for ten to fifteen seconds before allowing 

 it to dry. 



Thin Blood-films. — To make blood-films take perfectly clean 

 glass-shdes, free from any trace of grease, and lay them flat 

 on a clean piece of paper. Sterilize a needle in the flame, 

 and prick the dorsum of a finger just below the root of the nail. 

 Pick up one of the clean shdes, invert it, and towards one end 

 just bring it in contact with the oozing blood. Too large 

 a drop must not be taken. Re-invert the shde on the table 

 and, taking another slide, with a smooth even edge as a spreader 

 hold in at an angle of 45°, touching the drop so that a thin 

 film of blood runs between the edge of the spreader and the 

 shde. When the blood has spread along the edge, push the 

 spreader fairly rapidly toward the other end. The blood must 

 follow the spreader and not be pushed before it. A thin 

 film will result covering about one-half of the shde. Allow 

 the film to dry in air, covering it, if necessary, with a Petri 

 dish to protect it from flies, dust, etc. In monsoon weather 

 haemolysis may take place before the film has time to dry, 

 and at such times the film should be held, as soon as made, 

 over a spirit-lamp flame to dry. Films are usually stained 

 by one of the modifications of Romanowsky's stain. 



Staining the Dried Blood-films. — The films, as prepared 

 above, may be stained with the original Romanowsky's stain, 

 or with one of the many modifications, such as Leishman's 



