74 Microscopic Histochemistry 



scope, nuclei are blue and mucin intensely pink. Rinse thor- 

 oughly in water, dehydrate rapidly in absolute acetone or 

 alcohol, clear in xylene, and mount in balsam. Mucin, carti- 

 lage ground substance, and mast cells appear in shades of 

 purple-blue to purple-red; nuclei, clear blue. Metachromasia 

 of interfibrillar substance of connective tissue is greatly weak- 

 ened by dehydration; this substance must be studied in 

 unstable, water-mounted sections. 



b) Celestin blue.— Dissolve 0.1 per cent celestin blue in a 

 5 per cent solution of ammonium ( or potassium ) aluminum 

 sulfate. Stain sections in this solution for 2-3 hours. Rinse 

 under the tap, dehydrate, and mount. The color contrast is 

 less brilliant than with toluidin blue but much more resistant 

 to alcohol. 



Hale's technique for acid polysaccharides.— Hale described 

 a technique^^ for the demonstration of acid polysaccharides, 

 based upon the adsorption of colloidal iron hydroxide on 

 acidic tissue components. In a second step the adsorbed iron 

 is converted into Prussian blue. 



While the method sometimes gives a most beautiful and 

 selective staining of some types of mucin, it cannot by any 

 means be considered a specific method for acid polysac- 

 charides. Not even all types of mucin are stained by it, but 

 only those which are metachromatic with toluidin blue; the 

 nonmetachromatic mucus of the stomach and of Brunner's 

 glands is left entirely unstained. According to Grishman,^^ 

 even some types of metachromatic mucin are negative with 

 Hale's stain. Mast cells, which contain a strongly acid poly- 

 saccharide, also stain very poorly. For connective-tissue poly- 

 saccharides, Hale's method is greatly inferior to the Mc- 

 Manus stain in respect to both sharpness and uniformity of 

 results, especially after fixations other than alcohol. It usually 

 stains chromatin quite intensely; in addition, there is a dif- 

 fuse light-blue tinge to the background. 



In summary, the specificity of Hale's method is not limited 

 to any chemically defined substance. The method will be de- 



