and Laboratory Methods. 2041 



8. Hermann's Fluid. — Miiller (1892) used Hermann's fluid for the study of 

 the nuclei of leucocytes and nuclear structure. 



1 per cent, platinic chloride, - - - 15 



2 " " osmic acid, - - - - 4 



Acetic acid, - . - - i 



Fix either fresh or dry preparations several days to a month (Miiller recom- 

 mended ten days), wash in running water twelve to twenty-four hours, stain. 



9. Mercuric Chloride.— Hlava (1883), Kruse (1890), and Van der Strecht 

 ( ) fixed dry preparations in sublimate solution. Kruse usQ^d a concentrated 

 watery solution, in which the preparations remained five to ten minutes, then 

 five minutes in absolute alcohol to which was added iodine tincture, five minutes 

 in pure alcohol, stain. Van der Strecht fixed the air-dried preparations twelve 

 to twenty-four hours in a 2 per cent, solution of sublimate in a physiological salt 

 solution, then one hour in absolute alcohol with iodine, several hours in pure 

 absolute alcohol, washed in water, stained. 



10. Mercuric Chloride= Alcohol. — Argutinsky (1901) used a sublimate-alcohol 

 solution for fixing blood films for the study of malarial parasites. Seven grains 

 of pure sublimate are dissolved in 100 c. c. of a 1 per cent, hot aqueous solution 

 of sodium chloride, and when cool 100 c. c. of absolute alcohol is added. The 

 dry preparations are subjected to this fixative for five to eight minutes, then 

 washed in strong alcohol for a few minutes and transferred to iodine alcohol. 

 This solution is prepared by adding 1 gram of pure iodine to 100 c. c. of abso- 

 lute alcohol. After rinsing in absolute alcohol and drying between filter paper, 

 the preparations are ready to slain. 



11. Picric Acid.— Miiller (1 891),Hock and Schlesinger (1892), and Mannaberg 

 (1893) used picric acid fixation. Miiller, in his study of leukaemic blood, fixed 

 heated dry preparations twenty-four hours in a concentrated watery solution of 

 picric acid, washed in running water 12 to 24 hours, and stained. 



12. Picric Acid and Acetic Acid. — Mannaberg (1891) and Hock and Schlesinger 

 (1892) employed a picric and acetic acid mixture. Mannaberg gives the follow- 

 ing formula : 



Saturated watery solution of picric acid, - - 30 

 Distilled water, ------- 80 



Glacial acetic acid, - - - - - - 1 



Fix dry preparations for two hours in this solution. 



13. Zenker's Fluid. — Whitney (1901) recommends a modified Zenker's fluid 

 for fixing dry blood films. Zenker's fluid, in which 5 per cent, of strong nitric 

 acid is substituted for the 5 per cent, cf glacial acetic acid, is allowed to act on 

 the film for a few seconds (count 20), wash with running water. Ehrlich's 

 " triacid " solution, Una's polychrome methylen blue and Chenzinski's eosin and 

 methylen blue mixture are said to work well after this fixation, but Loffler's alka- 

 line methylen blue gives a fine precipitate on the red corpuscles. 



III. STAINING THE PREPARATIONS. 



The stains used in staining the blood may be divided into three groups 

 depending upon the position of the active staining property in the dye. Dyes 

 in which a staining base is combined with an inert acid as methylen blue, methyl 



