THE MICROSCOPE. 



the bacilli are numerous, they could be seen with so faulty a back- 

 ground of color as this, but when they are few they might easily 

 •escape notice. A drop or two of a saturated watery solution of 

 methyline blue let fall upon the sputum after the nitric acid has 

 been washed out will bring them into relief. The blue color is 

 washed off to a certain extent with water, just enough of it being 

 left to give a distinct light blue tint to the sputum. Examine the 

 specimen while still wet, with a power of 500 diam. When gentian 

 violet is used, the background should be given by Bismarck brown. 



At the same meeting Heneage Gibbes, M. D., presented the 

 following as an easy and simple method for the demonstration of 

 the bacillus: Make two staining fluids — one magenta, which stains 

 the bacillus; the other chrysoidin, which stains the surrounding sub- 

 stance. The magenta solution is made thus: Magenta crystals, 

 two grammes, are rubbed in a glass mortar to a fine powder, dis- 

 solve three cubic centimetres of pure aniline in twenty c. c. of alco- 

 hol sp. gr. 830, add this to the powder, stirring until all the color is 

 dissolved; then add twenty c. c. of distilled water slowly, still stir- 

 ring, and put in a stoppered bottle. 



The chrysoidin solution is made by rubbing up the color in a 

 mortar with distilled water until it is saturated and then adding a 

 crystal of thymol dissolved in a little absolute alcohol, to make it 

 keep. Neither of these solutions should be filtered when made. 

 The latter should be kept in the dark. A solution, one part nitric 

 acid with two parts of distilled water is also required. 



Prepare cover glasses as described in the former method. Fil- 

 ter a few drops of the magenta solution into a watch-glass and place 

 on it a prepared cover-glass with the sputum downwards, care being 

 taken that no air-bubbles are under the cover-glass; it should remain 

 from fifteen to twenty minutes in the solution. It is then put into 

 the dilute nitric acid until all color has been removed. It is then 

 washed in distilled water until the acid is removed, and placed in a 

 few drops of chrysoilin solution which have been filtered into an- 

 other watch-glass; a few minutes will suffice to stain it deeply. It 

 must then be again washed in distilled water, and the superfluous 

 water drained off on filter paper; it is then to be placed in absolute 

 alcohol, to remove the remainder of the water, and dried thoroughly 

 in the air. When dry a drop of Canada balsam solution is placed on 

 the cover-glass and it is mounted in the usual manner. 



