BLOOD AND GLANDS 395 



stains, else they will wash off; but this is not necessary for 

 alcoholic stains, 



869. Films of Bone Marrow. A small piece of bone marrow 

 may be teased in serum on a slide. Afterwards this is spread on 

 a slide as in the case of blood films, and stained by one of the 

 Romanowsky stains. Mallory {Pathological Technic, 1924) 

 recommends that the film be fixed for one minute, while still wet, 

 with methyl alcohol or one of the usual fixatives, after which 

 staining is carried out. Price-Jones {Journ. of Path, and Bad., 

 1910, xiv, p. 218) uses the following : Small pieces are transferred 

 to a watch-glass containing a dissociating reagent where a more 

 or less complete emulsion results and cellular elements of the 

 tissue are dissociated. The dissociating solution consists of 

 glycerin diluted with ammonia-free distilled water to form a 

 10 per cent, neutral solution, titrating against N/10 NaOH and 

 using phenolphthalein as indicator. The initial acid reaction 

 should vary from + 0-1 to -f 0-5 Eyre's scale and the reagent 

 has a specific gravity of 1-029 at 15-7° C. A loop-full of this 

 glycerin solution is placed on a coverslip and to this is added a 

 loop-full of the emulsion in the watch-glass and very gently 

 spread over the surface of the slip. The film thus prepared is 

 allowed to dry in the air without heating until a uniform ground- 

 glass appearance is produced. Treat as a blood film with Jenner 

 and after a thorough washing in ammonia-free distilled water 

 and complete drying in air mount in xylol, balsam. 



870. Fixing and Preserving in Bulk. Most morphologists are 

 agreed that by far the most faithful fixing agent for blood cor- 

 puscles is osmic acid. A drop or two of blood (Biondi recom- 

 mends 2 drops exactly) is mixed with 5 e.c. of osmic acid solution, 

 and allowed to remain in it for from one to twenty-four hours. 

 As a rule, the osmic acid should be strong — 1 to 2 per cent. Fixed 

 specimens may be preserved for use in acetate of potash solution 

 (Max Flesch, Zeit. iviss. Mik., v, 1888, p. 83). 



Griesbach also (ibid., 1890, p. 328) combines the osmic acid with 

 certain stains. He mentions methyl green, methyl violet, crystal 

 violet, safranin, eosin, Saurefuehsin, rhodamin and iodine in potassium 

 iodide. 



Rossi {ibid., vi, 1889, p. 475) advises a mixture of equal parts of 

 1 per cent, osmic acid, water, and strong solution of methyl green, 

 permanent mounts being made by means of glycerin cautiously added. 



EwALD {Zeit. Biol., xxxiv, 1897, p. 257) mixes 3 to 4 drops of blood of 

 amphibia or reptiles with 10 e.c. of a solution of 0-5 per cent, osmic acid 

 in 0-5 per cent, salt solution (for mammals 0-6 to 0-7 per cent, salt), 

 siphons off the supernatant liquid after twenty-four hours with his 

 capillary siphon and substitutes water, alum, carmine, etc., and lastly, 

 50 per cent, alcohol. 



Weidenreich {Arch. mik. Anat., Ixxii, 1908, p. 213) lays a cover 

 with a drop of blood on it on a layer of agar-agar (1 per cent, in salt 

 solution of 0-8 per cent.) and after five minutes runs in osmic acid of 

 1 per cent., and after five minutes more removes the cover. 



