On Staining. 31 



wholly immersed, and then it must not be left long 

 or the stain will be too deep, and it cannot be after- 

 wards removed. 



This is one of the most useful of the anilins soluble 

 in water, and the results when it is carefully used are 

 very beautiful ; it picks out all the nuclei, and in grow- 

 ing bone it colours the unossified cartilage, giving a 

 very striking result. It is also a most valuable anilin 

 in double staining ; its action will be described under 

 that head. 



16. Bismarck Brown. This is a good colour, a deep 

 rich brown. It is easily soluble in spirit but does not 

 make a very deeply coloured solution, it stains well. 

 An aqueous solution can be made by the addition of a 

 little dilute acetic acid, this solution also stains well 

 but it remains to be seen whether it will fade or not. 

 The aqueous solution stains gland tissue well, and in a 

 section of tongue where the mucous glands are deeply 

 stained with the aqueous solution, the colour has not 

 faded after an exposure of two months. It is doubtful 

 as yet which will prove to be the best solution, the 

 aqueous is decidedly the richest colour to the eye but 

 must be kept for a week, after making, before it is 

 used. 



ANILIN DYES SOLUBLE IN SPIRIT. 



17. Spiller's Purple. This is a very good colour for 

 use in double staining, but it is very difficult to fix it 

 and if the section is passed through methylated spirit, 

 it will be almost all washed out ; it is not quite so easily 

 acted on by strong absolute alcohol, '795 sp. gr., but 



