154 H^MATEIN 



282. Heidenhaix's Iron Haematoxylin * (M. Heidenhain, 

 " Uber Kern und Protoplasma," in Festschr. fiir Kolliker, 1892, 

 p. 118). Sections are treated from half an hour to at most two 

 or three hours Avith a 1-5 to 4 per cent, solution of ferric alum 

 (ammonio-ferric sulphate). By this is always meant in histology 

 the double salt of ammoyiium and sesquioxide of iron (NH4)2Feg 

 (804)4, ""i clear violet crystals ; the double salt of the protoxide, 

 or salt of MoHR in green crystals, will not serve. If the crystals 

 have become yellow and opaque, they have gone bad, and should 

 be rejected. They ought to be kept in a stoppered bottle, and 

 the solution should be made in the cold [Arch. mik. Anat., xliii, 

 1894, pp. 431, 435). The sections are then washed with water 

 and stained for half an hour in an aqueous solution (of abovit 0-5 

 per cent.) of haematoxylin. They are then rinsed with water, 

 and again treated with the iron solution, which slowly washes 

 out the stain. The j^rogress of the differentiation ought to be 

 controlled under the microscope. The sections should to this 

 end be removed from time to time from the alum solution, and 

 put into tap-water whilst they are being examined. This is 

 favourable to the stain. As soon as a satisfactory differentiation 

 has been obtained, the preparations are washed for at least a 

 quarter of an hour in running water, but not more than an hour, 

 and mounted. The results differ according to the duration of the 

 treatment with the iron and the stain. If the baths have been of 

 short duration, viz. not more than half an hour in the iron and as 

 much in the stain, blue preparations will be obtained. These 

 show a very intense and highly differentiated stain of nuclear 

 structures, cytoplasmic structures being pale. If the baths in 

 the iron and in the stain have been prolonged (twelve to eighteen 

 hours), and the subsequent differentiation in the second iron 

 bath also duly prolonged, black preparations will result. These 

 show chromosomes stained, central corpuscles stained intensely 

 black, cytoplasm sometimes colourless, sometimes grey, in which 

 case achromatic spindle-fibres and cell-plates are stained, con- 

 nective-tissue fibres black, red blood-corpuscles black, micro- 

 organisms sharply stained, striated muscle very finely shown. 



Later {Zeit. wiss. Mik., xiii, 1896, p. 186) Heidenhain gives 

 further instructions for the employment of this stain in the study 

 of central corpuscles. All alcohol should be removed from the 

 tissues by means of distilled water before bringing them into the 

 mordant. This should be a 2^ per cent, solution of ferric alum, 

 not weaker. Leave the sections therein (fixed to slides by the 

 water method, § 208) for six to twelve hours, or at least not less 

 than three. Keep the slides upright in the mordant, not lying 

 flat. Wash out zcell with water before staining. Stain in a 

 " ripened " haematoxylin solution, i.e. one that has stood for four 



* See also §§ 627, 693, 1365. 



