34 MANUAL OF BACTERIOLOGY. 



tubercle bacilli with smegma bacilli. (See smegma bacilli in 

 Part II., Chapter IV.) 



Patients should be given minute instructions concerning the 

 collection of sputum. The bottle used should be new, wide- 

 mouthed, clean, and kept tightly stoppered with a clean cork. 

 The patient should be cautioned against allowing the expec- 

 toration to get on the outside of the bottle. Probably what- 

 ever risk is incurred by those who examine sputum comes 

 chiefly from the outside of the bottle having been soiled with 

 sputum containing tubercle bacilli. Often little white particles 

 may be seen floating in the mucous portions of the sputum. 

 These particles should be selected for the investigation, and 

 may be spread in a thin film on the cover-glass with the plati- 

 num wire, which is sterilized in the flame before and after 

 using. The selection of the little white particles will be facili- 

 tated if the sputum be poured into a clean glass dish, which 

 may be placed on a black surface. A form of porcelain dish is 

 furnished by dealers, the bottom of which is black, and which 

 is convenient, for these manipulations. The smears must be 

 made thin, or the subsequent decolorization, after staining, will 

 not be uniform. It is hardly necessary to observe that the 

 operator must be scrupulously careful not to contaminate the 

 material under examination with any kind of extraneous 

 matter. The cover-glasses and slides which are used should be 

 new, and should have been cleaned with bichromate of potas- 

 sium and sulphuric acid (see page 25). 



When the work is completed, the bottle containing the 

 sputum should be sterilized by steam or boiling. 



Many different methods for staining the tubercle bacillus 



have been proposed. In most of those now in use the following 



solution (Ziehl's carbol-fuchsin) is employed— 



F"chsi° I gram. 



Carbolic acid, pure . . . . c c c 



Alcohol . . . 'jo ^^ 



Distilled water . joo f.^. 



N. B.— Acid fuchsin cannot be used for this stain. 



