2. STAINING METHODS, 



The following are a few simple methods, in constant 

 use, arranged with special attention to convenience in 

 laboratory work^: 



I. STAINING BACTERIA IN COVER-GLASS PREPA- 

 RATIONS WITH WATERY SOLUTIONS OF 

 AISriLINB DYES.' 



1. MAKING THE OOVEK-GLASS PREPAEATIONS. 



(a) From Fluid Parts of the Body. — With the steri- 

 lized straight or small looped platinum-needle place a 

 small drop of blood or of pus upon the weU-cleaned cover- 

 glass and spread it out upon the latter in as even and as 

 thin a film as possible; or, with a sterilized knife, a scrap- 

 ing from the freshly-cut surface of the organ to be ex- 

 amined is spread out in a like manner; or, the cover-glass 

 is pressed directly against the freshly-cut surface of the 

 organ. 



(Before cutting an organ burn the surface where the cut is to be 

 made with the flat side of a very hot knife.) 



(b) From Pieces of Tissue. — ^With sterilized forceps 

 pull out a small particle of tissue from the freshly-cut sur- 

 face of the organ, crush between the forceps, and spread a 

 portion of this crushed tissue substance ^with the plati- 

 num-needle or the points of the forceps) upon the cover- 

 glass as above directed. 



2. "FIXING" THE COVER-GLASS PREPARATION. 



To fix the preparation the cover-slip is held in the 

 forceps high abcve the flame, "butter" side uppermost, 



iFor anthrax, symptomatic anthrax (black-leg), hog cholera, mouse 

 septicsemia, typhoid fever, gonocoecus, tetanus, pus organisms, etc., 

 and probably all saprophytic bacteria. 



2 SOLUTIONS OF THE ANILINE DYES: (a) of the dye, 2 

 parts; water 85 parts; boil from five to ten minutes, and after cool- 

 ing add 15 parts of 90 per cent, alcohol; mix thoroughly and filter 

 twice, (b) Requisite amounts of concentrated alcoholic solations of 

 the dyes are diluted ten times with water. 



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