1890.] MICKOSCOPICAL JOURNAL. 85 



made to define the term "Amateur," as distinct from the professional 

 man, but so tar entirely without success. vSo far as microscopical work 

 is concerned, the expense and time required will prevent any from 

 engagincr in it who have not a real love for it that will tend in any case 

 to a higher plane of intellectual character, if not to substantial contri- 

 butions to knowledge. 



But on the latter point, many of the most imjDortant additions to our 

 scientific literature have been made by men who were amateurs, if that 

 term is applied to men who do not make a business, or gain a liveli- 

 hood, by the exercise of science. Rutherford, Tulasne, Dallinger, 

 Wolle, Strecker, etc., are amateurs, and the character of their contri- 

 butions to microscopy and other sciences fully justify the admission of 

 amateurs to consideration as scientific men and fellow-workers for the 

 increase of our knowledge of absolute truth. 



Aniline Stains for Microscopic Objects.* 



By HERR HUEPPY. 



The basic aniline colors are soluble in water, and for the most part 

 in one or all of the decolorizing agents in use a weak waterv solution 

 colors at first the intercellular substance and the cell body, while the 

 nuclei remain unstamed. Through the subsequent treatment with alco- 

 hol, glycerine, or acetic acid an inversion of the staining takes place, 

 by which the elements previously colored become colorless and the pre- 

 viously colorless nuclei are stained. In the use of the stronger solu- 

 tions the staining follow^s (without any discernible inversion) directly 

 and quickly, and, in general, its intensity is in proportion to the concen- 

 tration of the solution. In a quite concentrated watery solution over- 

 staining may occur, which can be reduced to the proper degree by sub- 

 sequent decolorization. 



If the dyes are dissolved in the decolorizing agents— such as abso- 

 lute alcohol, acetic acid, or thick glycerine — thev stain slightlv or not 

 at all. Instead of using some decolorizing agent subsequently to reduce 

 the intensity of the staining to a proper degree in preparations which 

 have been overstained in watery solutions, in manv cases a solution of 

 the dye-stuft'in a mixture of water with alcohol (Hermann), glvcerine 

 (Schaefer), or acetic acid (Ehrlich) may be used. 



The basic aniline dyes are used in the follow^ing solutions : 



(i.) Concentrated watery solutions. These are either used directly, 

 or after dilution to the desired degree with distilled water. The solu- 

 tions are prepared with distilled water (which has been previously 

 boiled) , so that an excess of the coloring-matter remains undissolved. 

 They must always be filtered before using. Only a small quantitv of 

 these watery solutions should be made at a time. 



(2.) Concentrated alcoholic solutions. The solution of an excess of 

 the coloring material is brought about in the best way bv absolute alco- 

 hol, or, in want of this, by the officinal 90 per cent, spirit of the Phar- 

 macopcEia. 



In general, one can calculate about 20 to 25 grammes of the dye-stufi 

 to 100 grammes of the spirit or alcohol. These solutions are kept pre- 



* " Di^Iethoden der Bakterien-Forschung." 



