] 78 CHAPTJilli XIV. 



Flem.U[N(j's ai-id dlfferentiafciou {Zelt. wlsii. Bilk., i, 1884.', 

 p. 350). — Differentiate; until hardly any more colour comes 

 away, in alcoliol acidulated with about O'o per cent, of 

 hydrochloric acid, followed by pure alcohol and clove oil. 

 (You may use the IlCl in watery solntioii if you prefer it.) 

 Or you may use a lower strength, viz. O'l per cent, at most 

 (see Arcli. mile. Anat., xxxvii, 1891, p. 249) ; and this I find 

 is generally jDreferable. 



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. 



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

 differentiates (for from a few seconds to two minutes) in a 

 strongly alcoholic 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 Geam (see next section). This process has also 

 been recommended by Peenant {Int. Monatsschr. Anat., etc., 

 iv, 1887, p. 368). 



It has been shown by Ohlmachbk (Journ. Amer. Med. Assoc, vol. xx, 

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

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

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

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

 The precipitate is formed both in normal and pathological tissue, 

 readily in carcinomatous tissues ; and Ohimacher concludes that many 

 of the bodies that have been described as " ooccidia," " sporozoa,'' or 

 other " parasites " of carcinoma are nothing but particles of this pre- 

 cipitate. 



See also the differentiation x^rocess of Maetinotti and Bbsegotti 

 (Zeit. iviss. Mile, iv, 1887, p. 328) for alcohol-fixed material ; and of 

 Gabbini {Zeit. iviss. Mil:, v, 2, 1888, p. 170). 



In preparations made with chromo-aceto-osmic acid, 

 safranin stains, besides nuclei, elastic fibres, the cell bodies of 

 certain horny epithelia, and the contents of certain gland- 

 cells (mucin, under certain imperfectly ascertained condi- 

 tions) . 



The stain is jDerfeotly permanent. 



287. Gentian Violet may be used in aqueous solution, or as 

 directed for safranin. 



