NUCLEAR STAINS, COAL TAR 185 



Flemmixg {Arch. mik. Anal., xix, 1881, p. 317) used a con- 

 centrated solution in absolute alcohol, diluted with about one- 

 half of water. 



Babes {ibid., 1883, p. 356) used (a) a mixture of equal })arts 

 of concentrated alcoholic solution and concentrated aqueous 

 solution (this is very much to be recommended), or (b) a con- 

 centrated or supersaturated aqueous solution made with the aid 

 of heat. 



Some people still employ simple aqueous solutions. 



The anilin solution of Babes {Zeit. rviss. Mik., iv, 1887, p. 470) 

 consists of water 100 parts, anilin oil 2 parts, and an excess of 

 safranin. The mixture should be warmed to from 60° to 80° C, 

 and filtered through a wet filter. This solution will keep for a 

 month or two. 



Zwaardemaker {ibid., iv, 1887, p. 212) makes a mixture of 

 about equal parts of alcoholic safranin solution and anilin water 

 (saturated solution of anilin oil in water ; — to make it, shake up 

 anilin oil with water and filter). This will keep for many months, 

 perhaps indefinitely. 



Lee uses equal parts of saturated solution in anilin water and 

 saturated solution in absolute alcohol. 



Differentiation. — For general directions see § 367. 



Flemming's acid differentiation {Zeit. wiss. Mik., i, 1884, 

 p. 350). Differentiate, until hardly any more colour comes 

 away, in alcohol acidulated with about 0-5 per cent, of hydro- 

 chloric acid, followed by pure alcohol and clove oil. (You may 

 use the HCl in watery solution if you prefer it.) Or you may 

 use a lower strength, viz. 0-1 per cent, at most (see Arch. mik. 

 Anat., xxxvii, 1891, p. 249) ; and this is generally preferable. 



Objects are supposed to have been well fixed — twelve hours 

 at least— in the strong chromo-aceto-osmic mixture, and stained 

 for some hours. In this way you get kinetic chromatin and 

 nucleoli alone stained. 



PoDWYSSOZKi {Beitr. z. Path. Anat., i, 1886, p. 289) differentiates 

 (for from a few seconds to two minutes) in a strongly alcohol 

 solution of picric acid, followed by pure alcohol. Same results 

 (except that the stain will be brownish instead of pure red). 



Babes recommends treatment with iodine, according to the 

 method of Gram (see next section). This process has also been 

 recommended by Prenant {Int. Monatsschr. Anat., etc., iv, 

 1887, p. 368). 



It has been shown by Ohlmacher {Journ. Amer. Med. Assoc., vol. xx. 

 No. 5, February 4th, 1893, p. Ill) that if tissues be treated with iodine 

 or picric acid after staining witli safranin, there may be produced in the 

 tissue elements a precipitate of a dark red substance of a crystalline 

 nature, but of lanceolate, semilunar, falciform, or navicellar forms. 

 The precipitate is formed both in normal and pathological tissue, 

 readily in carcinomatous tissues ; and Ohlmacher concludes that many 



