BACTERIOLOGICAL TECHNIQUE 21 



7. Decolorize in chloroform or clove oil, and repeat the applica- 

 tion until the decolorization is complete. ' Clove oil is the better of 

 the two for permanent specimens. 1 



8. Dry and mount in Canada balsam, dissolved in xylol. 

 Result. The bacteria are stained a deep indigo blue. 



This stain has very little affinity for fungi cells and other histo- 

 logical elements, whilst its affinity for certain bacteria is somewhat 

 extraordinary. The bacteria stained by the Gram method also stain 

 by this method, as also the bacillus of malignant oedema. 



XIII. ZIEHL-GABBET METHOD OF STAINING TUBERCLE 

 BACILLI IN COVER-GLASS PREPARATIONS. 



1. Spread a small portion of the material, 'sputum, caseous mass, 

 mucus, etc., that is most likely to contain the bacilli, 1 upon a clean 

 cover-glass in as thin a layer as possible. 4 Gunther considers it is 

 dangerous in making' cover-glass specimens from sputum to rub two 

 cover-glasses together and then separate them, as the caver-glasses might 

 break, cutting the finger, and thus inoculating the operator? 



(In examining the sputum of suspected tubercular and asthmatic 

 patients much time is saved by using the sputum attachment of the 

 hand centrifuge, see Fig. 7, 20.) 



2. Air dry, and fix by passing three times through the Bunsen flame. 



3. Place some Ziehl-Nielsen's carbol fuchsin (see 51) in a watch 

 glass or small porcelain evaporating dish, and float the cover-glass on 

 the surface, material side downwards ; heat the stain until vapour 

 arises, and set aside one minute to allow the stain to work. ' Another 

 method is to flood the cover-glass with the stain, and heat three or 

 four times until vapour arises. 1 



4. Wash the cover-glass in water to remove excess stain. 



5. Place the cover-glass in Gabbet's solution (see 52) one to 

 three minutes, according to the thickness of the preparation and the 

 intensity of the fuchsin stain. 



6. Wash in water, dry. 



7. Mount in xylol balsam. 



XIV. METHOD OF STAINING TUBERCLE BACILLI IN 

 COVER-GLASS SPECIMENS WITH EHRLICffS ANILIN 

 WATER STAIN. 



This method is recommended by Gunther. 



1. Prepare the material on the cover-glass in the same manner as 

 described under 1 and 2 processes, Ziehl-Gabbet method, 13. 



