BACILLUS OF TUBERCULOSIS. 307 
When we wish to thoroughly exclude mouth bacteria 
a lump of the sputum raised by a natural cough is seized 
by the forceps and transferred to a bottle of sterile 
water and thoroughly shaken ; it is then removed to a 
second bottle of bouillon and again thoroughly shaken. 
From this it is passed in the same way through four 
other bottles of bouillon. A portion of the mass is 
now smeared over cover-glasses, and the rest inoculated 
in suitable media, such as agar in Petrie dishes, and 
ascitic Auid bouillon in tubes. If desired the bacteria 
washed off in the different washings are allowed to 
develop. 
Practical Notes on the Examination for Mixed Infec- 
tion. 1. The difficulties to be overcome, in order to 
obtain sputum consisting presumably of exudate from 
the deeper portions of the lungs, are so great that the 
collection of the specimens should be supervised by the 
bacteriologist in charge of the work of examination. 
2. Specimens of sputum collected even with the 
greatest precaution may give evidence of decided 
mouth infection unless immediately washed. 
3. The sputum must be examined very soon after 
collection. 
4, The culture medium used for the final cultures 
must be suitable for the growth of the micro-organisms. 
5. At least two successive examinations of sputum 
should be made in each case. 
6. The results, especially as to the number of colo- 
nies, vary according to the size and tenacity of the ball 
of sputum washed—e. g., a small ball of sputum which 
becomes more or less broken up upon thorough shaking 
may contain very few or no bacteria. 
Williams, in the examination of the sputum in some 
