xoo SCIENCE REMAKING THE WORLT5 



fluenza lurked in many centers preceding the pandemic 

 of 1918. Which ever of these divergent places of origin 

 proves to be the true one, certain essential conditions 

 (as yet undiscovered) must be regarded as combining 

 to convert smouldering inactivity into epidemic spread. 



THE EPIDEMIC OF 1918. The emergency created by 

 the epidemic outburst of 1918, which was of unparalleled 

 severity, coincided with the exigencies of the Great War 

 so that the full weight and force of modern methods 

 of clinical and bacteriological study could not quickly 

 be brought to bear upon the disease. In many instances 

 investigators were further handicapped through failure 

 to distinguish influenza as a primary infection from the 

 frequent pneumonias of common bacterial origin which 

 were secondary to it; or were prejudiced in their views 

 by the general acceptance of Pfeiffer's bacillus as the 

 bacterial cause of influenza. This bacillus had been 

 discovered by Richard PfeifFer during the epidemic of 

 1889. 



Early in the course of the epidemic, however, discor* 

 dant findings cast doubt on the part played by Pfeiffer's 

 bacillus as the cause of the disease and in many labor- 

 atories the search was started de novo for some hitherto 

 unknown microbe whose distribution and character 

 would more nearly fit the requirements of the case. 

 The results of such an investigation at the Rockefeller 

 Institute for Medical Research are described in this 

 chapter. 



DEFINITION OF EPIDEMIC INFLUENZA. Epidemic in- 

 fluenza free from complications is usually a mild affec- 

 tion. On the fringes of an epidemic it is not always 



