BACTERIUM INFLUENZA 425 



microorganism that is claimed to stand in causal relation 

 to influenza. 



This organism, bacterium influenzse, as it is called, was 

 discovered, isolated, cultivated and described by R. Pfeiffer. 



By appropriate methods of staining it is also frequently 

 possible to demonstrate the presence of bacterium influenzse 

 in the secretions of the nose, mouth, and throat of appar- 

 ently healthy persons, as well as in those from persons 

 suffering from such diseases as diphtheria, scarlet fever, 

 measles, etc. 



It appears to be a widely distributed organism. These 

 facts are of importance and must be borne in mind in con- 

 nection with the contention that Bacillus influenzse is not 

 the cause of influenza, but is only an early invader after the 

 disease has been started by some other, as yet unknown, 

 living virus. 



Between the epidemic of 1889-90 and that of 1918 opin- 

 ion was in general concordant in regarding this bacillus 

 as the exciting cause of influenza. During and since the 

 outbreak of 1918, however, there has been a divergence 

 of opinion on the subject; some still believing in the 

 etiological relationship of Pfeiffer's bacillus to the disease, 

 others regarding it as only a secondary, though early, invader 

 after the disease itself has been started by some other living, 

 transmissible agent. Just what that agent is cannot now be 

 said, but there is some ground for believing that it may be 

 one of the so-called filterable, ultramicroscopic, amorphous 

 viruses. 



If this latter view should ultimately prove to be correct, 

 we shall still have not only Bacillus influenzse, but pneu- 

 mococci and streptococci, as very early invaders in practic- 

 ally cases, and as agents with which we must reckon; for 



