HENNEGUY'S PERMANGANATE METHOD. 71 



enable a good stain to be procured in cases in which the usual 

 methods fail. 



Sections (from tissues fixed either in the strong solution of 

 Flemming for from two to six hours, or in other reagents 

 such as sublimate, liquid of Perenyi, liquid of Kleinenberg, 

 alcohol, &c.) are treated for five minutes with 1 per cent, 

 solution of permanganate of potassium. They are then 

 washed with water and stained (for about half the time that 

 would have been taken if they had not been mordanted with the 

 permanganate) in safranin, rubin, gentian violet, vesuvin, or 

 the like. The stain that succeeds the best is a safranin solu- 

 tion prepared with anilin water and absolute alcohol (see 

 above, 101). After staining they are washed out with 

 alcohol, followed by clove oil in the usual way. This is the 

 delicate part of the process. The progress of the decolora- 

 tion must be watched under the microscope, in order that it 

 may be stopped at the proper moment. It goes on in general 

 slowly, and the slower it proceeds the more selective will be 

 the resultant stain. The decoloration sometimes continues 

 even after the sections have been mounted in balsam, espe- 

 cially if all traces of clove oil have not been removed before 

 mounting. It may thus happen that preparations which are 

 insufficiently washed out at the moment of mounting show a 

 perfectly differentiated stain twenty-four or forty-eight hours 

 afterwards. 



If safranin have been taken as the stain the preparations 

 show protoplasm of an orange- grey tint, which shows up the 

 most delicate structures, in particular the achromatic figures 

 of cytodieresis. Chromosomes and nuclear membranes are of 

 a brilliant red, attractive spheres and centrosomes less 

 Strongly stained, but still sharply brought out against the 

 rest of the cytoplasm. 



If it be desired to have the details of protoplasmic structures 

 still more markedly brought out, the safranin stain may be 

 preceded by haematoxylin staining (O5 per cent, solution of 

 haematoxylin in 90 per cent, alcohol ten minutes, wash 

 with water, treat for ten minutes with 2 per cent, solution of 

 bichromate of potash, and wash with distilled water before 

 treating with the permanganate). But with preparations 

 that have been fixed in Flemming this treatment will hardly 

 be necessary. 



