326 BACTERIOLOGY. 
abscess formation. Bacilli are found in fatal cases 
to have penetrated from the bronchial tubes not only 
into the peribronchitic tissue, but even to the sur- 
face of the pleura, and rarely they have been obtained 
in pure cultures in the purulent exudation. The pleu- 
risy which follows influenza, however, is usually a 
secondary infection, due to the streptococcus or pneu- 
mococcus. Ordinarily influenza runs an acute or sub- 
acute course, and not infrequently it is accompanied by 
mixed infections, with the pneumococcus and the strep- 
tococcus. Pfeiffer was the first to draw attention to 
certain chronic conditions depending upon the influenza 
bacillus. According to this observer, these bacilli may 
be retained in the lung tissue for months at a time, 
remaining latent awhile, and then becoming active 
‘again, with a resulting exacerbation of the disease. 
Consumptives are particularly susceptible to attacks of 
influenza. Williams, in the examination of washed 
sputa in cases of pulmonary tuberculosis, has on numer- 
ous occasions found abundant influenza bacilli, and this 
in the summer, when no influenza was known to be 
present in New York. Taken together with Pfeiffer’s 
results in Berlin, this indicates that at all times of the 
year many consumptives carry about with them influ- 
enza bacilli, and that very likely many healthy persons 
also harbor a few. Given proper climatic conditions, 
we have at all times the seed to start an epidemic. 
The influenza bacillus does not occur, as a rule, in 
the blood. According to Pfuhl and Nauwerck, the 
influenza bacilli have been found in the interior organs 
and the brain, but these observations require further 
confirmation. So far as positive results have shown, 
influenza would seem to be a local infection confined to 
