166 NUCLEAR STAINS WITH COAL-TAR DYES. 



divers degrees of electivity that it displays for the nuclei and other 

 constituent elements of different tissues. 



The great secret of staining with safranin is to get a good safranin. 

 In ordering it, from Griibler & Hollborn or elsewhere, it is well to 

 specify whether you want it for staining nuclei or for staining elastic 

 fibres, or for what other purpose you may require it. There are 

 presumably at least a score of sorts of safranin in the market, 

 differing to a considerable extent in colour, weight, solubility, and 

 histological action. Some are easily soluble in water and not so in 

 alcohol, some the reverse, and some freely soluble in both. The 

 brand I have been using for a long time, which gives good results, is 

 the " Safranin " of Griibler & Co. 



Staining. The majority of safranins are not sufficiently soluble 

 in water, so that solutions in other menstrua must be employed. 



PFITZNER (Morph. Jahrb., vi, p. 478, and vii, p. 291) advised a 

 solution of safranin 1 part, absolute alcohol 100 parts, and water 

 200 parts, the last to be added only after a few days. 



FLEMMING (Arch. mik. Anat., xix, 1881, p. 317) used a concen- 

 trated solution in absolute alcohol, diluted with about one-half of 

 water. 



BABES (ibid., 1883, p. 356) used (A) a mixture of equal parts of 

 concentrated alcoholic solution and concentrated aqueous solution 

 (this is very much to be recommended), or (B) a concentrated or 

 supersaturated aqueous solution made with the aid of heat. 



Some people still employ simple aqueous solutions. 



The anilin solution of BABES (Zeit. wiss. 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, I find, will keep for many months, perhaps 

 indefinitely. 



I myself use equal parts of saturated solution in anilin water and 

 saturated solution in absolute alcohol. 



Differentiation. For general directions see 281 and 282. 



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 hydrochloric acid, followed 

 by pure alcohol and clove oil. (You may use the HC1 in watery 



