CHAPTER XI I L 151 



245. JANSSENS' Iron Haematoxylin (" H6matoxyline noire"; La 

 Cellule, xiv, 1897, p. 207). A similar mixture to that of DELAFIELD, 

 ferric alum being taken instead of ammonia alum, the rest as in 

 Delaneld's. A progressive stain, nuclear : for yeast cells. 



246. HANSEN'S Iron Haematoxylin (Zeit. wiss. Mik., xxii, 1905, p. 55). 

 A solution of 10 grms. ferric alum in 150 c.c. water is added to a 



solution of 1-6 grm. hsematoxylin in 75 c.c. water, the mixture heated 

 to boiling-point and cooled without access of air. Filter before use. 

 To get a pure nuclear stain, add dilute sulphuric acid. 



247. Aluminium Hsematein (Alum Hsematoxylin) Generalities.- 



The mordant and dye are generally combined in a single staining 

 bath, giving a progressive stain. The stain is in different tones of 

 blue or red according to the composition of the staining solution. 

 Neutral or alkaline solutions give a blue stain ; acid solutions give 

 a red one. In order to get a blue stain in preparations that have 

 come out red through the acidity of the staining bath, it is a common 

 practice to treat them with weak ammonia, in the belief that the 

 blue colour is restored by neutralisation of the acid that is the cause 

 of the redness. According to MAYER, the ammonia acts, not by 

 neutralising the acid, but by precipitating the alumina, which carries 

 down the hsematein with it (if no alumina were present the colour 

 would be purple, not blue). The same result can generally be 

 obtained by merely washing out with common tap-water, which is 

 usually sufficiently alkaline, and can be obtained with certainty by 

 treatment with bicarbonate of soda or acetate of soda or potash. 

 And this is the preferable course, as ammonia is certainly a dangerous 

 thing to treat delicate tissues with. See SCOTT'S tap-water substi- 

 tute, 676. Of course this is a different question from that of 

 neutralising with an alkali tissues that have been treated with an 

 acid to correct over-staining. Here the neutralisation may be 

 indicated in the interest of the preservation of the stain. 



SQUIRE (Methods, p. 22) finds that sections can be blued in a few 

 seconds by treatment with a 1 : 1000 solution of bicarbonate of 

 soda in distilled water. MAYER holds that acetate of potash is the 

 most inoffensive reagent to take ; a strength of 0-5 to 1 per cent, 

 may be taken. 



Several of these solutions have a great tendency to over-stain. 

 Over-stains may be corrected by washing out with weak acids (e.g. 

 0-1 to 0-2 or even 0-5 per cent, of hydrochloric acid, or with oxalic 

 or tartaric acid), but this is not favourable to the permanence of the 

 stain. CARNOY (La Cellule, xii, 2, 1897, p. 215) recommends iodised 

 water. If acids be used, it is well to neutralise afterwards with 

 ammonia or bicarbonate of soda (0-1 per cent.). 



