BACILLUS OF TUBERCULOSIS. 305 
fluid. The sedimentation may be obtained more quickly 
by the centrifugal machine. 
TI, Examination for Other Bacteria (Mixed Infection). 
With regard to the bacteriological diagnosis of pul- 
monary phthisis, many consider that it is not enough 
to show only the presence of tubercle bacilli; it is held 
to be of equal importance, both for purposes of prognosis 
and treatment, that the presence of other micro-organ- 
isms which may be associated with the tubercle bacillus 
should also be determined. It is now usual to dis- 
tinguish pure tuberculosis of the lungs from a mixed 
infection. Phthisis due to the tubercle bacillus alone, 
which constitutes but a small percentage of all cases, 
may occur without febrile reaction; or when fever occurs 
the prognosis is unfavorable, thus indicating that the 
disease is already advanced. It is in the uncomplicated 
forms of phthisis, moreover, where one must expect if 
anywhere the best results from treatment with tuber- 
culin or antituberculous serum. The majority of cases, 
however, of pulmonary tuberculosis show a mixed in- 
fection, especially with varieties of the streptococcus 
and pneumococcus. These cases may be active, with 
fever, or passive, without fever, according, perhaps, 
as the parenchyma of the lung is invaded by the bac- 
teria; or they are only superficially located in cavities, 
bronchi, etc. Mixed infection with the staphylococcus 
and with the influenza and pneumonia bacilli have 
also been frequently met with by us. The tetragenus 
has not been detected by us in thoroughly washed 
fresh sputum, but has been found by others. At present 
the facts seem to prove that the tubercle bacilli have 
in the great majority of cases at least until shortly 
20 
