9 ESSENTIALS OF BACTERIOLOGY. 



decolorizing agent ; but the preparations are not permanent ; 

 the method, however, is very useful. 



Two solutions are required : one of Ziehli's carbol-fuchsin ; 

 the other Gabbet's acid methylin blue. (See No. X., on 

 page 33.) 



The cover-glass containing the dried sputum is passed three 

 times through the flame, as described in the general directions. 

 It is then placed in the carbol-fuchsin solution live minutes (cold), 

 or two minutes in the hot, immediately then transferred to the 

 second solution, the acid blue, where it remains one minute, 

 then washing in water. The preparation is dried between filter- 

 paper, and mounted best first in water. Examined with oil- 

 immersion. 



Aiwtlwr Raitid Method. This method possesses the advan- 

 tage of giving permanency to the preparations ; but the bacilli 

 are distorted and ugly crusts form. 



Three dishes are required : 



The first contains nitric acid and water 1-4. 



The second alcohol. 



The third distilled water. 



They are arranged one after the other in the above order. 



Two staining solutions must be at hand, carboi-fuchsin and 

 watery methylin blue. The cover-glass containing the dried 

 sputum is passed three times through the flame, then covered 

 with a, few drops of carbol-fuchsin, and held in the forceps over 

 the flam?, so that the stain will boil upon the glass. With a 

 pipette the dye is constantly added and kept boiling for about 

 one minute. It is then decolorized by holding it in the first 

 dish until it appears brownish-black, then directly into the 

 second dish, when the alcohol peals off the red color in little 

 clouds, and it becomes nearly colorless ; about five seconds 

 suffice. Then it is placed in the third dish, the water washing 

 oft' the alcohol. If the color of the preparation is now deeper 

 than a slight pink, it is again dipped into the acid, alcohol, and 

 back into the water, careful not to hold it too long in the above 

 solutions. The contrast stain is now applied, a few drops of the 

 methylin blue solution left on cold for two minutes being suffi- 

 cient. The glass is now dried and mounted on the slide in 



