64 BACTERIOLOGICAL DIAGNOSIS. 
. INFLUENZA. 
The diagnosis of influenza is often very difficult, and 
a simple bacteriological examination should be made 
in all cases. The cultivation of the specific bacillus 
is by no means easy, but this does not matter, as an 
examination of stained films will usually permit of a 
diagnosis. : 
The influenza bacillus occurs in the sputum and 
occasionally in the blood. It may be searched for in 
the latter situation, but the quest is a very difficult one. 
In the sputum it occurs in vast quantities and is almost 
free from other germs. 
The method by which the sputum is collected is the 
same as that employed in pneumonia; a mass of 
greenish-yellow muco-pus is selected for examination, 
squeezed between two slides, and the films dried and 
fixed as in the case for the examination for the tubercle 
bacillus. One is stained for five minutes with dilute 
carbol-fuchsin or Léffler’s blue, the slide being slightly 
warmed, and the other by Gram’s method. 
EXAMINATION OF THE SPECIMENS. 
The specimen stained with carbol-fuchsin or Léffler’s 
blue should be taken first and examined under the oil 
immersion lens. The bacilli (in a positive case) will 
be seen in vast numbers as extremely minute rods; it 
would take from twelve to sixteen of these rods to make 
up the diameter of a red blood corpuscle. They fre- 
quently occur within the pus cells, and when in this 
