IRON H^MATOXYLIN. 129 



pische Schdume u. das Protoplasma, &c., 1892; Zeit. f. wiss. 

 Mik., ix, 2, 1892, p. 197). Sections treated with a weak 

 brown aqueous solution of ferric acetate, washed with water, 

 and stained in O5 per cent, aqueous solution of hsematoxylin. 

 This treatment gives a blue-black or brown-black stain of 

 extraordinary intensity. The process was used by Biitschli 

 for staining sections, 1 /j. in thickness, of Protozoa. 



197. Iron Haematoxylin (M. HEIDENHAIN, "Uber Kern und 

 Protoplasma," in Festschr. Herrn Geheimr. A. v. Kolliker, fyc.j 

 gewidm., 1892, p. 118; Zeit. f. wiss. ffik., ix, 2, 1892, p. 204). 

 Sections are treated from half an hour to at most two or 

 three hours with a 1*5 to 4 per cent, solution of aminonio-sul- 

 phate of iron: (NH 4 ) 2 Fe 2 (SOJ 4 . They are then washed with 

 water, and stained for half an hour to twelve hours in an 

 aqueous solution (of about 0'5 per cent.) of hsematoxylin. 

 They are then rinsed with water, and again treated with the 

 iron solution, which slowly washes out the stain. As soon as 

 a satisfactory differentiation has been obtained, the prepara- 

 tions are washed for a quarter of an hour in running water, 

 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 differen- 

 tiated stain of all nuclear structures, achromatic as well as 

 chromatic, cytoplasmic structures being pale. If the baths 

 in the iron and in the stain have been prolonged, and the 

 subsequent differentiation in the second iron bath also duly 

 prolonged, black preparations will result. These show 

 chromosomes stained, central and polar bodies stained in- 

 tensely black, cytoplasm sometimes colourless, sometimes 

 grey, in which case achromatic spindle-fibres and cell-plates 

 are stained, connective-tissue fibres black, red blood-corpuscles 

 black, micro-organisms sharply stained. 



198. Weigert's Haematoxylin. This method, which is the 

 inverse of Heidenhain's ( 193), is only applicable to nerve- 

 tissues, and therefore will be described in the chapter on 

 Nerve Methods" in Part II. 



199. Minot's Haematoxylin Methods (Zeit.f. wiss. Mik., iii, 2, 1886, 



9 



