CHAPTER XVIII. 



INFLUENZA, PLAGUE, RELAPSING FEVER, 

 MALTA FEVER, YELLOW FEVER. 



INFLUENZA. 



THE first account of the organism now known as the 

 influenza bacillus was published simultaneously by Pfeiffer, 

 Kitasato, and Canon, 



in January 1892. The - \r''J ' '"? 



two first - mentioned *, * i. 



observers found it in ^f v . **5tJ? v V* . 



the bronchial sputum, 

 and obtained pure cul- 

 tures, and Canon ob- 

 served it in the blood 

 in a few cases of the 

 disease. It is, however, 

 to Pfeiffer's work that 

 we owe most of our 

 knowledge regarding 

 its characters and ac- 

 tion. From the facts 

 which have been 

 established concerning 

 it, this organism has 

 strong claims to be considered the specific agent in the 

 disease, though absolute proof is still wanting. 



Microscopical Characters. The influenza bacilli as seen 



- , < 







bacilli from a culture 



Stained with carbol-fuchsin. x 1000. 



