328 BACTERIOLOGY. 
well characterized by its morphological, staining, and 
cultural peculiarities that it may be distinguished with 
sufficient certainty for practical purposes from all other 
bacteria by an expert bacteriologist who is familiar 
with it. The only bacillus which resembles it at all 
closely is the pseudo-influenza bacillus found by Pfeiffer 
in three cases of bronchopneumonia. This bacillus is 
culturally very similar to the true bacillus influenze, 
but may be distinguished from it by its larger size and 
tendency to grow out into long threads. It is not cer- 
tain but that it is a form of the influenza bacillus. 
There is no doubt that other infections are also included 
under the clinical forms of influenza, and during an 
epidemic bronchopneumonias, irregular types of lobar 
pneumonias, and cases of bronchitis frequently have 
symptoms so closely alike that the nature of the bac- 
teria active in the case is very frequently different from 
that supposed by the clinician. Thus in four consecu- 
tive autopsies examined by the writer the influenza 
bacillus was found almost in pure culture in one case 
believed to be due to the pneumococcus, and entirely 
absent in two of the three believed to be due to it. 
Except for these examinations the clinician would be 
of the opinion that he had clearly diagnosticated bacte- 
riologically the cases, while in fact he had been wrong 
in three of the four. 
The striking symptoms in acute respiratory diseases 
are frequently more due to the location and amount of 
the poisons than to the special variety of organisms pro- 
ducing them. 
