STAINS AND STAINING. 287 



fashion for the last ten years. Since the mention of this " ammo- 

 niated haematoxylin " in my " Methods and Formulae " there has 

 been some talk of using haematein instead of haematoxylin in 

 Ehrlich's solution. This is, of course, the natural suggestion, but 

 commercially haematein is a very variable product, frequently next 

 to useless for staining purposes, and I have yet to meet with a 

 commercial sample even of ammoniated haematein capable of 

 staining nuclei with such a depth of rich colour and definition as 

 an ammoniated haematoxylin prepared on the lines I have indi- 

 cated. The formula at present stands thus : — 



Ammoniated Hcematoxylm {Squire). 



Haematoxylin, 15 grms. ; ammonium carbonate, 3 grms. ; proof 

 spirit, 300 c.c. ; place in a large bottle and shake at intervals for 

 three days, leaving the stopper out between the shakings. Allow 

 the solution to evaporate to dryness in an open dish at the tem- 

 perature of the air, and (substituting the crystalline product thus 

 obtained for haematoxylin in the ordinary formula) dissolve in the 

 following mixture: — Absolute alcohol, 750 c.c. ; glycerine, 750 c.c; 

 distilled water, 750 c.c. ; ammonia alum, 15 grms. ; glacial acetic 

 acid, 75 c.c. 



Colow Produced by Haematoxylin. 



Haematoxylin solutions stain the nuclei violet, and in order to 

 change this into blue it is usual to soak the sections in water taken 

 from the house supply (not distilled water), but as the alkalinity of 

 the water varies in different localities, a better and more uniform 

 result is obtained by using a weak solution of bicarbonate of 

 sodium (^ grain to the ounce). 



With the view of testing whether strong daylight and alkali 

 were essential to the formation of the blue, I placed some sections 

 in glazed earthenware covered pots with distilled water recently 

 boiled in platinum. The violet colour gradually became blue, 

 but there is no doubt that the change is much assisted by an 

 alkali. After the blue colour is developed, if the sections are not 

 for immediate mounting, they should be kept in the dark, and in 

 70 per cent, alcohol. If kept in water they fade rather quickly 

 when exposed to daylight, and are bleached by direct sunlight. 



