140 STAINED PREPARATIONS 



(v) Complex stains. 

 Roux's blue. 

 SOLUTION A. 



Violet dahlia, 1 gram. 



Absolute alcohol, - - 10 grams. 



Distilled water, - - Q.S. for 100 grams. 



SOLUTION B. 



Methyl-green, 2 grams. 



Absolute alcohol, - 20 



Distilled water, - - Q.S. for 200 grams. 



1. Prepare each solution separately by rubbing up the dye with the alcohol 

 in a mortar and add the water gradually. Let the mixture stand for 24 hours 

 in a bottle. 



2. Then mix the two solutions, filter and store in a well-stoppered bottle. 



2. Simple staining-. 



For purposes of staining there should be at hand 



(a) Several small glass funnels and a number of pieces of filter paper 

 folded to fit them. Staining solutions ought always to be filtered before 

 being used and should be dropped from the filter straight 

 on to the preparation. 



(b) A wash-bottle filled with water recently filtered through 

 a Chamberland filter (fig. 126). This bottle is so arranged 

 that by simply tilting it the water runs out through the 

 glass tube. 



(c) In the absence of a sink, a large glass dish to collect 

 the washings. 



(d) A number of slides and cover-glasses, a pair of Cornet's 

 or Debrand's forceps, platinum needles, a piece of soft cloth, 

 some small squares of filter paper or a packet of cigarette 

 papers and a few Pasteur pipettes. 



(e) A Bunsen burner with a pilot flame. 



(i) The methods of staining living organisms. 



The object of staining living organisms is to make them 

 FlG ' 1 botS W * dl " more readily visible for microscopical examination while at 

 the same time preserving their motility. 



For this purpose aqueous solutions of dyes which have no toxic action on 

 the organisms are used e.g. vesuvin (Metchnikoff), methyl-green (Babes), 

 quinoline blue, fuchsin, neutral-red, etc. 



Technique. Make the preparation in the same way as for the examination 

 of unstained living organisms. Invert the cover-glass on the slide and run 

 a drop of a watery solution of the dye along the edge of the cover-glass ; by 

 capillary action it will be drawn between the cover-glass and slide. 



Or if preferred a small drop of the stain can with a very fine pipette be 

 added to the culture on the cover-glass and the two solutions mixed with the 

 end of the pipette ; the cover-glass is then inverted on the slide and the 

 preparation is ready for examination. 



(ii) The staining of dried films. 



This is the best method of examining the morphology of micro-organisms 

 and it gives moreover preparations which are practically permanent. 



Technique. A. 1. Pick up a cover-glass with a pair of Cornet's forceps, 



