H^MATEIN 157 



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 })ermanent 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 haematein 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. 



Formulic §§ 288 to 299 give aqueous solutions, and §§ 300 to 

 303 alcoholic ones. 



288. Mayer's Haemalum, Later Formula {Zeit. wiss. Mik., xx, 

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

 and add 0-2 grm. of iodate of sodium (NalOg) and 50 grm. 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 hcematein (or the ammonia salt, 

 §§ 278, 279) dissolved with heat in 50 c.c. of 90 per cent, alcohol, and 

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



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

 stable by adding 50 grm. 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 best.) After staining, sections may be washed 

 out either with distilled or tap water. It is admirable 

 for staining in hulk. Large objects will, however, require 

 twenty-four hours' staining, and should be washed out for 

 the same time (this should be done with 1 per cent, alum 

 solution if a sharp nuclear stain be desired). All alum must be 

 carefully washed out of the tissues before mounting in balsam ; and 

 it is well to blue the stain with tap-water or otherwise, § 1429 bis. 

 The stain is generally a nuclear one ; in any case such may be 

 obtained by washing out with alum-solution. Mayer's pre- 

 parations have kept well in glycerin (care being taken not to 

 have it acid), also in balsam. If oil of bergamot be used for clear- 

 ing, it must be thoroughly removed by means of oil of turpentine 

 before moimting, and oil of cloves is dangerous. It is best 

 (Mayer, in Hit.) to use only xylol, benzol, or chloroform, and to 

 mount in xylol-balsam or chloroform-balsam or benzol-balsam. 



Haemalum mav be mixed with alum-carmine, Siiurefuchsin, or 



