80 LABORATORY BACTERIOLOGY 
counterstaining. (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 acidulated alcohol 
or a 10% solution of sulphuric acid, and stain one by Gabbett’s 
ee 
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 (1) morphology, 
(2) cultural properties, and (3) pathogenesis. v ~“feeences. 
Measure the tubercle bacteria in one of the preparations and 
make a drawing showing a few of them magnified 1000 diameters. 
Inoculate the media in groups A and B with the culture 
furnished of Bact. suisepiicus or some other member of the 
septicemia hemorrhagica group.(aviseplic/s -paskeure 4a.) 
120. 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, and then to dry, fix, and stain as with the cover 
glasses. The water is dried off by using filter or blotting paper, 
and the preparation is 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. 
