1508 Journal of Applied Microscopy 



NORMAL AND PATHOLOGICAL HISTOLOGY. 



Joseph H. Pratt. 



Harvard University Medical School, Boston, Mass., to whom all books and 

 papers on these subjects should be sent for review. 



MIchaelis, L. Ueber Fett-Farbstoffe. Virch- Much that relates to our histological 

 ow's Archiv fiir path. Anat. 164: 263-270, staining methods is purely empirical. 

 '^°'' Hence Dr. Michaelis' attempt to deter- 



mine chemically what part of the sudan III molecules gives the fat-staining 

 property, and from this knowledge to synthetically prepare a more satisfactory 

 stain, is very welcome. But why do we require a new stain or any stain for fat, 

 a substance so easily recognizable both morphologically and by its high index 

 of refraction ? Unfortunately other substances, as the zymogen granules of the 

 pancreas, eosinophilic granules, etc., are in these ways indistinguishable from fat. 

 Osmic acid is not specific and does not color all fat, for Altmann has shown that 

 osmic acid colors only the oleic acid fats. Sudan III has not proven perfectly 

 satisfactory. 



Sudan III is azobenzol-azo ft naphthol. Michaelis first assumes that the 

 double azo group lends the fat-coloring property to the molecule. However, he 

 finds that a stain with a simpler azo group (benzol-azo /j naphthol) will color fat. 

 Another stain, differing from last only in being a instead of ft naphthol, 

 stains tissues diffusely. This latter is soluble in alkalies, while the former is 

 soluble neither in alkalies nor acids, but only in organic solvents, thus resem- 

 bling Sudan III. In experimenting he finds that the staining reaction of the ft 

 compound does not depend on the orthoposition of the azo group to the OH 

 group, but in the lack of a free OH group- — in other words the lack of a salt- 

 forming group. So he concludes that fat-stains are those azo bodies which 

 possess no salt- forming group — indifferent coloring stuffs in opposition to acid 

 and basic. 



Knowing this, he prepares synthetically azoorthotulolazo ft naphthol (schar- 

 lach R or fettponceau), which gives better results than sudan III, coloring 

 very small droplets of fat bright red. This stain is insoluble in water, acids and 

 alkalies, soluble with difficulty in alcohol, and easily soluble in chloroform, fatty 

 oils and melted paraffin. 



The technique for its employment is — 



1. Tissues preserved in formol. 



2. Freezing microtome sections. 



3. Saturated solution of scharlach R in 60-70% alcohol for fifteen to 



thirty minutes. 



4. Counterstain with haematoxylin. 



5. Mount in glycerine or levulose syrup. H. A. Christian. 



Feldbausch, F. Ueber das Vorkommen von Goldmann, Miiller, Rieder, and Rein- 

 eosinophilen Leukocyten in Tumoren. Vir- bach have previously called attention 



chow's Archiv. f. path. Anat. 161 : 1-18, inoo. ^ ^, r 1 u^„^ ^t 



^ ^ to the presence of large numbers of 



eosinophilic leucocytes in certain tumors. 



