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 influenzse, 

 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. 



