128 ILEMATEJN AND OTHER OEGAN1C STAINS. 



Stain in a 1 per cent, solution of heematoxylin in 70 or 80 per 

 cent, alcohol. Wash out (for " thin" sections, i. e. sections of 

 10 to 15 n, half the time of staining for "thicker" sections 

 of 25 to 40 JJL twice the time of staining) in 1 per cent, solution 

 of bichromate of potash in 70 to 80 per cent, alcohol. 



The bichromate solution is conveniently prepared by mixing 

 one part of a 5 per cent, aqueous solution with about four 

 parts of 80 to 90 per cent, alcohol. The mixture should be 

 made immediately before using, and should be kept from the 

 light (light precipitates it) during the process of decolora- 

 tion, and should also be changed for fresh several times 

 during the process. After the differentiation of the colour 

 has been accomplished, the objects should be thoroughly 

 washed (still in the dark) in several changes of 70 per cent, 

 alcohol. 



Preparations made in this manner are more transparent and 

 better preserved than those made by Heidenhain's process. 



For staining celloidin series of sections, Apathy also (Zeit. 

 f. wiss. Mik.,vi,2, 1889, p. 170) recommends the following pro- 

 cedure : Stain in the haematoxylin solution as above for ten 

 minutes ; then remove the excess of haematoxylin fluid from 

 the sections by means of blotting-paper, and bring the series 

 for five to ten minutes into 70 per cent, alcohol containing 

 only a few drops of a strong (5 per cent.) solution of bichro- 

 mate. This must be done in the dark. If the heematoxylin 

 be not removed with blotting-paper as described, the celloidin 

 will take the stain. The sections should appear steel-blue to 

 steel-grey. 



195. MALLOEY'S Phospho-molybdic Acid Hsematoxylin (Anat. 

 Anzeig., 1891, p. 375 ; see also Zeit.f. wiss. Mik., viii, 3, 1891, p. 341). 

 One part of 10 per cent, phospho-inolybdic acid solution, 1 part haematoxylin, 

 100 parts water, and 6 to 10 parts chloral hydrate. Let the solution ripen 

 for a week in sunlight, and filter. This stain is recommended for prepara- 

 tions of central nervous system, but may perhaps be useful in other cases. 

 Sections should be stained for from 10 minutes to 1 hour, and washed out in 

 two or three changes of 40 to 50 per cent, alcohol. Dehydrate and mount 

 as usual. The celloidin remains colourless. The stain is blue, and in its 

 general effect something like a nigrosin stain. Besides ganglion-cells and 

 glia-cells, axis-cylinders are stained. It is necessary that the solution be 

 saturated with haematoxylin in order to obtain the best results ; if a good 

 stain be not obtained at once, more hiematoxylin must be added. 



196. Iron Haematoxylin (BUTSCHLI, Unters. fiber mikrosko- 



