1818 Journal of Applied Microscopy 



and carefully bring the solution to a boil. Then add carefully 6 gr. mercuric 

 oxid. When the mixture is dark purple remove from flame and cool rapidly. 

 Filter the stain, and add one drop of hydrochloric acid. Sometimes a flocculent 

 precipitate forms a short time after cooling, which dissolves on adding the acid. 

 The stain should be set aside for some weeks, as it does not usually give good 

 results at once ; this " ripening " process is variable, but when accomplished, the 

 stain keeps indefinitely. For staining immerse thin sections of tissue in it for 

 5 to 10 minutes. Wash for 1 minute in 1 per cent, nitric acid in alcohol, remove 

 acid alcohol with pure alcohol, clear, and mount. The author suggests the name 

 Elasthcemateifi, since it is closely related to Mayer's Muchaiiiatein. Tissue 

 treated with Mayer's mucicarmine and then with alcoholic solution of nitric acid 

 show the elastin more brilliantly stained than any other structure. 



A. M. c. 



Michaelis, L. Ueber Fettfarbstoffe. Virchow's The author Starts on a consideration of 



Arch., 164: 26-5-270, looi. , ^. ^ • <■ r ». j 



•^ ^ a selective stain for fats, pomades, par- 



affin, etc., and chooses alkannin in the form of the extract and a series of azo- 

 stains, among which Sudan III is the best known. This also works well on the 

 living over-fed animal or on the object fixed in formalin. Osmic acid is not 

 exclusive nor inclusive in its affinity for fat, it stains horn substance and only 

 fatty acids. Sudan III has a known definite composition, so that the author 

 has attempted to determine upon what property of the molecule the fat staining 

 propensity depends in order to discover systematically a better fat stain. A 

 number of azo-bodies were made, and the author came to the following results : 

 Fat-stains are those azo-bodies which possess no salt-forming group. He con- 

 siders them indifferent in contact with acid or basic forms. Scarlet R. (Fett- 

 ponceau of Kalle & Co., azoorthotoluolazo. — /i — Naphtol.) proves itself very 

 powerful. This stain is insoluble in water, acids, alkalies, slowly soluble in 

 alcohol, easily soluble in chloroform, fats, oils, and melted paraffin. In concen- 

 trated sulphuric acid it loses its blue color and becomes deep red and stains 

 even the smallest fat drop a shining red. Formalin hardened microtome sec- 

 tions or material prepared in other ways is put in a saturated solution of the stain 

 in 60 to 70 per cent, alcohol and stained 15 to 20 minutes. The nuclei may be 

 stained previously by the use of Boehmer's hematoxylin and the mounts made 

 in glycerine or levulose syrup. Glycerine is less clear, but does not affect the 

 hematoxylin. The author shows an interesting theoretical side to the question. 

 No stain shows more clearly that the process by which it acts is a physical and 

 chemical one. The molecule in order to be soluble in fat must be definite in its 

 chemical constitution. The results do not indicate the process to be merely 

 " solution," since the colors to affect the nucleus must be basic", and to give 

 results with the protoplasm must be acid. a. m. c. 



