GENTIAN VIOLET. 67 



of Gram in the paragraph on gentian violet, post, 102). This 

 process has also been recommended by PBENANT (Int. Monats- 

 schr. f. Anat., &c., iv, 1887, p. 368), who notes that the treat- 

 ment with the iodine solution should be somewhat longer, and 

 the treatment with alcohol somewhat shorter than with gentian 

 violet sections. 



MAETINOTTI and EESEGOTTI (Zeit.f. wiss. Mik., iv, 3, 1887, p. 328) reconT 

 mend washing out with a freshly prepared mixture of one part of O'l per 

 cent, aqueous solution of chromic acid with nine parts of absolute alco- 

 hol, followed by pure alcohol and bergamot oil. In my experience this 

 method does not give better results (I think less good) than that of washing 

 out in the simple aqueous solution of chromic acid of Bizzozero followed by 

 alcohol (see the paragraph on gentian violet, next ). The latter is certainly 

 a most useful method. It should be mentioned that Martinotti and Rese- 

 gotti's results refer to lightly stained alcohol-fixed objects, and not to 

 chromo-aceto-osmic objects, which may make a great difference. 



GAEBINI (Zeit. /. wiss. Mik., v, 2, 1888, p. 170) has recommended that 

 sections be dehydrated after staining in methylic alcohol (wood spirit) in 

 which safranin is only very slightly soluble, and decoloured in a mixture of 

 two parts of clove oil with one part of cedar oil. I have not been able to 

 obtain good results by this method. 



The reader will remember that safranin may be washed out by substitu- 

 tion (see ante, 98). 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. 



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 containing 

 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, semi-lunar, falciform or navicellar forms. This 

 precipitate is formed both in normal and pathological tissue, and occurs 

 either in the nuclei or in the cytoplasm. It is formed readily in carcino- 

 matous tissues ; and Ohlmacher makes out a strong case in favour of the 

 conclusion to which he has come that many of the bodies that have been 

 described as " coccidia," " sporozoa," or other " parasites " of carcinoma 

 are nothing but particles of this precipitate. This refers, amongst much 

 other work, to that of PODWYSSOZKI and SAWTSCHENKO. Forewarned is 

 forearmed ; but if the formation of Ohlmacher's precipitate should prove to 

 be a very general phenomenon, it will be necessary to conclude with him that 

 to follow safranin staining with treatment by solutions containing iodine or 

 picric acid is not only unscientific but positively dangerous. Of course this 

 is not intended to discredit the use of safranin when washed out with hydro- 

 chloric acid, alcohol, or the like. 



102. Gentian Violet. One of the most important of these 

 stains. It may be used in aqueous solution, or in alcoholic 

 solution diluted with about one half of water 



