380 BLOOD AND GLANDS. 



Air-dried films ought to be fixed before putting into aqueous or 

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

 for alcoholic stains. 



782. Fixing and Preserving in Bulk. Most morphologists are 

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

 is osmic acid. A drop or two of blood (BiONDi recommends two 

 drops exactly) is mixed with 5 c.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 speci- 

 mens may be preserved for use in acetate of potash solution (MAX 

 FLESCH, Zeit. wiss. 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, Saurefuchsin, rhodamin, and iodine in 

 potassic iodide. 



Eossi (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 cau- 

 tiously added. 



EWALD (Zeit. Biol., xxxiv, 1897, p. 257) mixes 3 to 4 drops of 

 blood of amphibia or reptiles with 10 c.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 ( 3, p. 4), 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. 



DEKHUYZEN (Anat. Anz., xix, 1901, p. 536) recommends a mixture 

 of either 3 or 9 volumes of 2 per cent, osmic acid with 1 of 6 per cent, 

 acetic acid, containing J per cent, of methylen blue, which he calls 

 " Osmacet." 



The mercurial liquids of Pacini ( 414) used to be considered 

 good. HAYEM (" Du Sang" etc., Paris, 1889 ; see also Zeit. wiss. 

 Mik., vi, 1889, p. 335) has the following formula : sublimate 0-5, 

 salt 1, sulphate of soda 5, and water 200. This should be mixed 

 with blood in the proportion of about 1 : 100. Eosin may be added 

 to it. LOWIT'S formula (Sitzb. k. Akad. Wiss. Wien, xcv, 1887, 

 p. 144) consists of 5 c.c. cold saturated sublimate solution, 5 grms. 

 sulphate of soda, 2 grms. salt, and 300 c.c. water. Mosso finds that 

 both of these are too weak in sublimate. 



