COAL-TAK CHKOMATJN STAINS. 203 



soluble in water, so that solutions in other menstrua must be 

 employed. 



A solution much used some time ago is that of PFITZNER 

 (Morph. Jalrb., vi, p. 478, and vii, p. 291), composed of saf- 

 ranin 1 part, absolute alcohol 100 parts, and water 200 parts, 

 the last to be added only after a few days. 



The solution of FLEMMING (Arch.f. mik. Anut., xix, 1881, 

 p. 317) is a concentrated solution in absolute alcohol, diluted 

 with about one half of water. 



The solutions of BABKS (Arch. /. mik. Anat., 1883, p. 356) 

 are (A) a mixture of equal parts of concentrated alcoholic 

 solution and concentrated aqueous solution (this is very much 

 to be recommended) , and (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 (Zeif. f. wiss. Mik., iv, 4,. 

 1887, p. 470) consists of water 100 parts, anilin oil 2 parts, 

 and an excess of safraniii. 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. 



ZWAAKDKMAKER (Zeit. f. u'l'stf. Mik., iv, 2, 1887, p. 212) 

 makes a mixture of about equal parts of alcoholic safraniii 

 solution and anilin water (saturated solution of aiiiliii oil in 

 water ; to make it,, shake up " anilin oil;" which is nothing 

 but pure anilin, 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. 



Any of these stains may be used with any of the following 

 differentiation processes. Of course you will have to stain 

 longer in the weaker solutions. As to the anilin solutions 

 see ante, 264. 



Differentiation. For general directions for differentiation 

 and clearing see above, 265 and 267. 



Neutral differentiation with pure alcohol, followed by 

 clove oil gives resting chromatin stained, as well as kinetic 

 chromatin. 



FLOIM ING'S <///'// differentiation (Zeif. /. /'/>*. Mil:., i, 3. 

 1884, p. 350). Differentiate, until hardly any more colour 

 comes awav, in alcohol acidulated with about 0*5 per cent, 

 of hydrochloric acid, followed by pure alcohol and clove oil. 



