500 



inucicarmine of P. Mayer ('96). My own experiments with these 

 staining fluids have been more fortunate and I have succeeded in 

 preparing a modified muchaematein which will stain not only these 

 cells of the rabbit glands of Brunner but also those of the glands of 

 B runner of every other mammal (20 species in all) upon which it 

 has been tried. 



I found at first that, using sublimate tissues, I could stain the 

 secretion in the cells of the glands of Brunner only if the sections 

 were free in the solution, that is, unattached to slides. I subsequently 

 found that by gradually increasing the strength of the solution with- 

 out altering the proportions of its solid constituents, a solution was 

 obtained which would act, with absolute certainty of positive results, 

 on sections fastened to slides by the usual water method, or on 

 sections cut in celloidin. The solution is prepared as follows: haematein, 

 1 g, aluminium chloride, 0,5 g, are rubbed up together in a mortar, 

 and dissolved in 100 ccm of alcohol diluted with tap-water to a 

 strength of seventy per cent. The solution stands one week, during 

 which it deepens somewhat in color, and increases in staining power. 

 At the end of this time, it is tested on a section. If the resulting 

 stain is slightly diffuse, a 10 per cent solution of nitric acid is added, 

 drop by drop, the staining properties being tested on a section after 

 the addition of each drop of acid. When the proper reaction is ob- 

 tained the mucin in cells will stain rapidly and deeply blue, the 

 cytoplasm and other tissues remaining unstained. Slightly over-acid 

 solutions will also give excellent results, except that the nuclei will, 

 in addition take a metachromatic red stain. The solution is applied 

 as follows: The sections cut in paraffin and fastened to the slide by 

 the water method are treated with benzole, followed by absolute 

 alcohol. The slide having been placed on the stage of the microscope, 

 a drop of the staining solution is applied with a pipette and the 

 section observed under the low power, until the secretion in the cells 

 is deep blue in color. The section is then rapidly washed in 70 per 

 cent alcohol, dehydrated, cleared in xylol, and mounted in balsam. If 

 the staining is prolonged and the solution is not renewed from time 

 to time, the sections after attaining a maximum depth of color, will 

 slowly fade out again, probably owing to reduction in the acidity of 

 the solution by the absorption of ammonia from the atmosphere. 

 Sections should not be washed in water after staining, as this pro- 

 cedure completely removes the stain from the mucous cells. The stain 

 may be rendered resistant to water by placing the slide for a few 

 moments in a saturated solution of neutral copper acetate in alcohol, 



