CHAPTER II. 



INFLUENZA. 



NOTWITHSTANDING a large number of bacteriologic 

 examinations conducted for the purpose of determining 

 the cause of influenza, it was not until 1892, after the 

 great epidemic, that there was found simultaneously by 

 Canon and PfeifFer a bacterium which conformed, at least 

 in large part, to the requirements of specificity. 



The observers mentioned found the same organism 

 one in the blood of influenza patients, the other in the 

 purulent bronchial discharges. 



The specific organisms (Fig. 99) are bacilli, very small 

 in size, having about the same diameter as the bacillus 



Jh * 



1 '*** '' 



'V^v'-' tf?V- 



FIG. 99. Bacillus influenzae, from a gelatin culture; x 1000 (Itzerott and 



Niemann). 



of mouse-septicemia, but only about half as long (o. 2 by 

 0.5 //). They are usually solitary, but may be united in 

 chains of three or four elements. They stain rather 



309 



