CHAPTER VIII. 



INFLUENZA. 



The specific organism was discovered in 1892 — Morphological characters 

 — Method of staining — Growth on media — Occurrence — Distribution 

 — Pathogenesis — Epidemics of note — The disease has produced dif- 

 ferent clinical effects in different years— An attack is not protective — 

 Prophylaxis. 



The organism causing this disease was first described by 

 Pfeiffer in the year 1892. It is found in the sputum and 

 blood of influenza patients during the febrile period ; it is a 

 very small rod not exceeding 1'5 /i in length and 0'3 /a in 

 thickness. It has rounded ends, and is generally found in 

 pairs, but on cultivation grows out into strings in a similar 

 way to anthrax. The limits of growth are from 26° to 

 42° C, the optimum temperature being that of the body. 

 It is aerobic and its powers of resistance to outside 

 influences are of a very low order. 



Method of Staining. — The bacillus stains with some 

 difficulty ; it is best stained with warm carbo-fuchsine, or 

 Loffler's methylene blue. It is not stained by Gram's 

 method. 



Growth on Media.— The influenza bacillus grows in stab 

 culture in grape-sugar agar at 37° C, in a thin whitish 

 streak, exhibiting no distinctive characters. On the surface 

 of glycerine agar on which a few drops of blood have been 

 smeared it forms small transparent colonies which are per- 



