So AIDS TO BACTERIOLOGY 



Bismarck Brown [(&) stain in Neisser's method for 

 diphtheria] : 



Bismarck brown . . . . . . 2 grammes. 



Distilled water (boiling) . . . . 1 litre. 



Filter. 

 Pugh's Stain for Klebs-Lomer bacilli, see p. 111. 



Leishman (p. 186), Jenner, picrocarmine, and Ehrlich- 

 Biondi triple stains are best bought ready prepared, 

 either in solution or in tablet form. All stains should be 

 kept in the dark when not in use. 



Cover-Glass Preparations. A small droplet of water is 

 placed in the centre of a clean cover-glass by means of 

 a sterile looped platinum wire. The mouth of the culture- 

 tube from which the preparation is to be made is singed 

 in the Bunsen flame. The plug is loosened by a rotary 

 motion, and partially withdrawn. An inoculating needle 

 (straight in the case of a streak culture, looped for a 

 broth culture) is heated to redness, the lower part of the 

 rod being also heated. The needle is held between the 

 right thumb and forefinger, and the plug is withdrawn 

 and held by the ring and little fingers of the right hand. 

 A trace of the growth (preferably from the margin in 

 the case of a streak culture, as the growth is youngest 

 there) is picked up. The needle is withdrawn and the 

 plug replaced. The growth is rubbed up with the drop 

 of water on the cover-glass, and spread over the surface 

 thereof. The needle is sterilised. The cover-glass may 

 be allowed to dry spontaneously, or may be held between 

 the fingers high over the flame. The film is now fixed 

 by passing the cover-glass, held in forceps, three times 

 through the Bunsen flame at the same rate as a clock's 

 pendulum swings. This fixing insures the film being 

 thoroughly dry, coagulates albuminous material, causing 

 adhesion of film to the glass, and may tend to diminish 

 the staining capacity of extraneous matter. A drop or 

 two of a filtered stain should now be dropped on the film, 

 or the cover-glass may be floated face downwards on the 

 stain contained in a watch-glass. The stain is allowed 

 to act for from two to ten minutes, according to the 

 preparation used. (The student should ascertain the 

 length of time which gives best results by experiment.) 

 To quicken the staining process, as is necessary in the 



