152 HMMATEIN (H^MATOXYLIN) STAINS. 



Bicarbonate of soda may be used for neutralisation with 70 per 

 cent, alcohol as the vehicle (VON WISTINGHAUSEN, Mittli. ZooL Stat. 

 Neapel, x, 1891, p. 41). 



Over-staining may be avoided by staining very slowly in dilute 

 solutions. The purest chromatin stains are obtained by staining 

 for a short time (sublimate sections half an hour, say) in solutions 

 of medium strength, such as hsemalum diluted ten to twenty-fold 

 with water. The stain obtained either with very strong solutions, 

 or with the slow stain of the dilute solutions, is at the same time a 

 plasma-stain, which of course may or may not be desired. MAYER 

 says that very dilute solutions will give a pure nuclear stain if they 

 have been diluted with alum- solution, or have been acidified. Chrom- 

 osmium material will not yield a pure chromatin stain unless it is 

 very fresh ; it is consequently next to impossible to obtain the 

 reaction with paraffin sections of such material ; they constantly 

 give a plasma-stain in addition to the chromatin stain, which is not 

 the case with sublimate material. 



The stain is fairly permanent in balsam, but is very liable to fade 

 a little, and may fade a great deal. If acids have been used after 

 staining, great care should be taken to wash them out thoroughly 

 before mounting. In aqueous media the stain cannot be relied on 

 to keep (this refers to the old solutions : MAYER finds that his 

 hsematein preparations have kept well for at least some months in 

 glycerin, if not .acid, and, with certain precautions, in balsam). 

 Turpentine-balsam should not be used. 



Formula 248 to 259 give aqueous solutions, and 260 to 263 

 alcoholic ones. 



248. MAYER'S Haemalum, Newer Formula (Zeit. wiss. Mik., xx, 

 1903. p. 409). Hcematoxylin, 1 grm. ; water, 1 litre. Dissolve, 

 and add 0-2 grm. of iodate of sodium (NaI0 3 ) and 50 grins, of alum, 

 dissolve and filter. 



This is an amended formula. The original one (Mitth. ZooL Stat. 

 Neapel, x, 1891, p. 172) was : 1 grm. of hamatein (or the ammonia salt, 

 238, 239) dissolved with heat in 50 c.c. of 90 per cent, alcohol, and 

 added to a solution of 50 grms. of alum in a litre of distilled water. 



This solution does not keep very well, but may be made more 

 stable by adding 50 grms. of chloral hydrate and 1 grm. of citric 

 (or acetic) acid. 



It stains equally well, either at first, or later. Concentrated, it 

 stains sometimes almost instantaneously, or in any case very rapidly. 

 (Spring water or tap-water containing lime must not be used for 

 diluting ; perhaps weak solution of alum in distilled water is the 



