135 



to stand for a week and again filter. Especially useful for 

 staining in bulk. 



Delafield's hcBmatoxylin (Lee, p. 184). — This is one of the 

 long used standard stains and can be bought, ready pre- 

 pared, of any dealer in microscopical supplies. The formula 

 for its making is as follows : " To 400 c.c. of saturated solu- 

 tion of ammonia alum (ammonia alum dissolves in about 11 

 parts of water) add 4 grams of haematoxylin crystals dis- 

 solved in 25 c.c. of strong alcohol. Leave it exposed to the 

 light and air in an unstoppered bottle for three or four days. 

 Filter and add 100 c.c. of glycerin and 100 c.c. of methylic 

 alcohol (CH^O). Allow the solution to stand until the color 

 is sufficiently dark, then filter and keep in a tightly stop- 

 pered bottle. ... It should be allowed to * ripen ' for at 

 least two months before using it." (Lee.) For staining, 

 some of this stock solution should be considerably diluted 

 with distilled water. We add a few drops of acetic acid (fol- 

 lowing Biitschli's suggestion) and get a much sharper stain. 



The color is blue, but the acetic acid produces a strong 

 reddish tinge. As this is an aqueous stain, the slide should 

 be carried from the 70^ alcohol (see p. 133) to a jar of dis- 

 tilled water before putting it into the jar of staining fluid. 

 The stain acts quickly, depending on the amount of dilu- 

 tion, and should be washed out with water. After washing 

 with water, the slide should be carried through 50^, 70^, and 

 into 96^ alcohol. It does not need differentiation (if acetic 

 acid has been added) and the albumen coating does not take 

 up the stain. 



Mayer s hcemalum (Lee, p. 182). — One gram of haematein 

 dissolved with heat in 50 c.c. of 90^ alcohol, and added to a 

 solution of 50 gr. of alum in a litre of distilled water. Allow 

 the liquid to cool and settle, and filter if necessary. A 

 quickly acting stain. After staining, the sections should be 

 washed in distilled water. 



