204 CHAPTER XV. 



(You may use the HC1 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 I 

 find 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 (if the fixation have 

 been performed as above directed). 



PODWYSSOZKI (Beitr. z. path. Anat., i, 1886 ; Zeit. f. u'iss. 

 Mile., iii, 3, 1886, p. 405) 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, for sections stained in the anilin solu- 

 tion, 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. Ass., vol. xx, 

 No, 5, Feb. 4, 1893, p. Ill) that if tissues be treated with solutions con- 

 taining 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 of lanceolate, semilunar, falciform, or navicellar 

 forms. This precipitate is formed both in normal and pathological tissue, 

 readily i* 1 carcinomatous tissues ; and Ohlinacher concludes that many of the 

 bodies that have been described as " coccidia," " sporozoa," or other 

 <c parasites " of carcinoma are nothing but particles of this precipitate. 



See also the differentiation process of MAETINOTTI and RESEGOTTI {Zeit. 

 /. wiss. Mik., iv, 3, 1887, p. 328) for alcohol-fixed material ; and of GARBINI 

 (Zeit. f. wiss. Mik. y 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 perfectly permanent. 



273. Gentian Violet. One of the best of these stains. It 

 may be used in aqueous solution, or in alcoholic solution 

 diluted with about one half of water (FLEMMING, Zells. Kern, 

 u. Zellth., 1882, p. 384), and the stain may be differentiated 



