HKIDENHAIN'S H^MATOXYLIN. 127 



p. 811 a complicated method of treating logwood. HICKSON, see Quart. 

 Journ. Mic. Sci., 1885, p. 244 a still more complicated method. COOK, see 

 Journ. of Anat. and Phys., 1879, p. 140 a sulphate of copper solution. 

 HATJG, see Zeit. f. wiss. Mik., viii, 1, 1891, p. 51 an acetate of alumina 

 solution. 



c. Other Hdemate'in Stains. 



193. Heidenhain's Haematoxylin (Arch. /. mik. Anat., 1884, 

 p. 468, and 1886, p. 383). Stain for twelve to twenty-four 

 hours in a \ per cent, solution of haematoxylin in pure water 

 (distilled water only should be used). Soak the objects for 

 the same length of time in a 0'5 per cent, solution of neutral 

 chromate of potash. Wash out the excess of chromate with 

 water, and treat further as desired. 



The above is a slightly modified form of the original pro- 

 cess, in which staining was done in a stronger hsernatoxylin 

 solution (O5 to 1 per cent.), and bichromate was used for 

 washing out instead of neutral chromate. The more recent 

 process gives a sharper chromatin stain. 



The stain succeeds best with alcohol or picric acid objects, 

 but it will succeed with chromic objects if they have been very 

 well washed. 



Objects that have been fixed in corrosive sublimate ought 

 to be very carefully washed out with water (many hours in 

 running water), as neutral hasmatoxylin forms a black preci- 

 pitate with the excess of sublimate that remains after wash- 

 ing out with alcohol (see TOENIEE, in Arch. f. mik. Anat., 1886, 

 p. 181). 



The stain is black to grey (haematoxylin forming with 

 chromic salts a black compound) . It is a sharp stain, remark- 

 ably rich in detail. 



The process is one well adapted to staining in the mass. 

 Perhaps its greatest advantage lies in the fact that you can 

 decolour the objects to any extent by prolonging the washing 

 in the chromate. 



The method may be varied by washing out after staining 

 with alum solution (1 per cent.) instead of a chromate. In 

 this case the stain will be blue. 



194. Apathy's Modification of Heidenhain's Process (Zeit. f. 

 wiss. Hik., v, 1, 1888, p. 47). This is an alcoholic method. 



