96 COCHINEAL AND OTHER ORGANIC STAINS. 







Ranvier re-dissolves this precipitate in 1 per cent, solution of alum, and 

 employs the solution for staining sections of epidermis that has been 

 hardened in bichromate of potash. The sections should remain twenty-four 

 hours in the liquid. Nuclei are then found stained light violet, the granules 

 of eleidin dark violet. 



177. Other Aqueous Alum-Heematoxylins. AENOLD, see Quart. 

 Journ. Mic. ScL, 1878, p. 86. MITCHELL, see Journ. Boy. Mic. Soc., 1884, 

 p. 811 a complicated method of treating logwood, so as to get rid of the 

 tannin, which is inimical to the preservation of the solutions. But why not 

 take Hcematox. crist. ? HICZSON, see Quart. Journ. Mic. Sci., 1885. p. 244 

 a still more complicated method of arriving at the same mare's nest. 

 COOK, see Journ. of Anat. and Phys., 1879, p 8 140, a sulphate of copper 

 solution. 



178. Heidenhain's Hsematoxylin (Arch. f. mik. Anat., 1884, 

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

 hours in a ^ per cent, solution of hasmatoxylin 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 hasmatoxylin 

 solution (0*5 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 haematoxylin forms a black preci- 

 pitate with the excess of sublimate that remains after washing 

 out with alcohol (see TORNIER, 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 



