92 LABORATORY BACTERIOLOGY 



Make 2 cover-glass preparations from the cultures furnished 

 for that purpose and stain them with carbol fuchsin ( 100). 



Make 4 cover-glass preparations from tuberculous sputum 

 and stain for tubercle bacteria. It is often desirable to counter- 

 stain the specimens from sputa. Stain 2 of them by Gabbett's 

 method and 2 with carbol fuchsin, and decolorize without 

 counters taining. 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. 



Examine the cultures of avian tubercle bacteria and describe 

 their appearance. Stain and examine a few preparations from 

 one of the cultures. 



Indicate in the notes the essential differences between human, 

 bovine, and avian tubercle bacteria respecting (i) morphology, 

 (2) cultural properties, and (3) pathogenesis. 



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. 



