BACTERIUM OF TUBERCULOSIS 87 



Stain the specimens from sputa. Stain two of them by Gabbett's 

 method, and two with carbol fuchsin and decolorize without 

 counter staining. Make a few (2 or 3) cover-glass prepara- 

 tions from the liver or spleen of a guinea pig which has died 

 from tuberculosis and stain them for tubercle bacteria. Stain 

 one with carbol fuchsin and decolorize with sulphuric acid, and 

 stain one by Gabbett's method. 



Indicate in the notes the essential differences between human 

 and bovine tubercle bacilli respecting (i) morphology, (2) cul- 

 tural properties, and (3) pathogenesis. Do these forms differ 

 from avian tubercle bacilli ? If so, in what respects ? 



Measure the tubercle bacteria in one of the preparations 

 and make a drawing showing a few of them magnified 1000 

 diameters. 



134. Making Cover-glass Preparations from Sputum Select 



the little yellowish colored masses, if present, remove them by 

 means of the fine forceps or platinum loop, and spread them 

 on the cover-glass in a thin layer. If the sputum is homoge- 

 neous, make the preparations the same as from cultures, using a 

 small loopful of the liquid. If the sputum is viscid, it is neces- 

 sary to use the forceps to spread the film on the cover-glass. 

 When dry, the films are fixed by passing the preparations 

 through the flame, after which they are ready to be stained. 



Instead of using cover-glasses, it is the practice in some labo- 

 ratories to spread the sputum in a thin film over the central 

 part of a slide ; dry, fix, and stain as with the cover-glasses. 

 The water is dried off by using filter or blotting paper, and the 

 preparation examined without a cover-glass. The method is 

 said to be easier and quicker than the other, and the cleaning 

 of cover-glasses is saved. 



135. Gabbett's Method of staining Tubercle Bacteria. 



(i) The stain (carbol fuchsin) ; — 



Fuchsin r gram. 



Absolute alcohol 10 c.c. 



S% carbolic acid 100 c.c. 



