io8 SCIENCE REMAKING THE WORLD 



ments proved beyond question the identity of the 

 active agent obtained from influenza cases and the 

 bodies obtained in culture. Both were derived from 

 the same sources. Both were filterable. Both pro- 

 duced identical effects in rabbits, and from the pulmon* 

 ary lesions produced by either, further animal passages, 

 or cultures, could be obtained. Both, protected by 

 bits of affected lung tissues, withstood 50 per cent, 

 glycerine for periods of months. Both had that curious 

 property of damaging the lung in such a way as to lower 

 its resistance to secondary invasion with ordinary bac- 

 teria. It was from this character that the microbe, 

 objectively, received its name. It was called Bacterium 

 pneumosintes a bacterium that injures the lung. 

 Finally, conclusive evidence of the identity of Bacterium 

 pneumosintes and the virus from the human nasal 

 washings was furnished by a series of experiments which 

 showed that a previous infection with either one of these 

 pathogenic agents rendered an animal immune to attack 

 by the other. 



IMMUNITY. In many infectious diseases, the im- 

 munity conferred by an attack is associated with the 

 appearance in the blood of specific principles, or "anti- 

 bodies," which can be demonstrated by serum tests. 

 Efforts were therefore directed toward the observation 

 of antibodies in the blood of experimentally infected 

 rabbits, and of influenza patients, from which the 

 strains of Bacterium pneumosintes ultimately had been 

 derived. But it was found that cultures of Bacterium 

 pneumosintes in the Smith-Noguchi medium were un- 

 suitable for such experiments. The sparse growth of 



