148 HMMATEIN (H^MATOXYLIN) STAINS. 



hsematein. but also some very bad ones ; presumably the solutions 

 easily over-oxidise on contact with the iron salt. 



The heematoxylin is generally dissolved in water. I frequently 

 prefer alcohol, of 50 per cent., as less injurious to tissues. 



The method is a regressive one. It has been proposed to stain 

 progressively, which I have tried, and had extremely bad results. 



The differentiation requires to be carefully timed. For this 

 reason the method is only applicable to sections, which should be 

 thin, best not over 10 /^. 



Iron hsematoxylin is one of the niost important of stains. It 

 enables us to stain elements which cannot be selectively stained in 

 any other way. The stain is very powerful, and of a certain optical 

 (jnalitij that is peculiarly suited to the employment of high powers : 

 it will allow of the use of deeper eye-pieces than other stains. It 

 will take effect on any material, and is quite permanent. Further 

 details as to the characters of the stain are given in 242. 



241. BENDA'S later Iron Haematoxylin (Verb. d. Anat. Ges., vii. 1. 

 1893, p. 161). Sections are mordanted for twenty-four hours in 

 liquor ferri sulphur id oxidati, P.G.,* diluted with one or two volumes 

 of water They are then well washed, first with distilled water, 

 then with tap water, and are brought into a 1 per cent, solution of 

 haematoxvlin in water, in which thev remain till they have become 



I/ V / 



thoroughly black. They are then washed and differentiated. The 

 differentiation may be done either in 30 per cent, acetic acid, in 

 which case the progress of the decoloration must be watched ; or 

 in a weaker acid, which will not require watching ; or in the sulphate 

 solution strongly diluted with water. 



I find that if the iron solution be taken for the differentiation, it- 

 should be taken extremely diluted (of a very pale straw-colour, about 

 1 : 30 of water), and the progress of the differentiation watched ; as 

 if it be only diluted about tenfold, for instance, the decoloration is 

 extremely rapid. See also last . 



I also find that Benda's mordant is unnecessarily, sometimes 



/ * 



harmfully, strong, and that the liquor ferri may be diluted tenfold 

 with advantage.- The duration of the bath in the mordant is also 

 for most purposes excessive as directed by Benda. I find that 

 three to six hours in the solution diluted tenfold is generally sufficient 

 with favourable material. 



* This preparation consists of sulphate of iron, 80 parts ; water, 40 ; 

 .sulphuric acid, 15 ; and nitric acid, 18, and contains 10 per cent, of Fe. 

 Doubtless the ferri persulphatis liquor B. P. will do instead ; the point 

 is, to have a per-salt, and not a proto-salt. 



