488 Influenza 



quickly and must be transplanted every three or four days if they are 

 to be kept alive. 



The organism is aerobic and scarcely grows at all where the supply 

 of oxygen is not free. 



In bouillon a scant development occurs, small whitish particles 

 appearing upon the surface, subsequently sinking to the bpttom and 

 causing a "wooly" deposit there. The bacillus grows more luxu- 

 riantly upon culture-media containing hemoglobin or blood, and can be 

 transferred from culture toculture many times before losing vitality. 



Vital Resistance. — ^Its resisting powers are very restricted, as it 

 speedily succumbs to drying, and is certainly killed by an exposure to 



Fig. 174. — Bacillus of influenza; colonies on blood agar-agar. Low magnifying 



power (Pfeiffer). 



a temperature of 6o°C. for five minutes. It will not grow at any 

 temperature below 28°C. 



Specificity.^ — From the fact that the bacillus is found chiefly in 

 cases of influenza, that it is present as long as the purulent secretions 

 of the disease last, and then disappears, and that Pfeiffer was able 

 to demonstrate its presence in all cases of uncomphcated influenza, it 

 seems that his conclusion that the bacillus is specific is justifiable. 

 It is also found in the secondary morbid processes following influenza, 

 such as pneumonia, endocarditis, middle-ear disease, meningitis, etc. 

 Horder* has cultivated it from the valvular vegetations of 2 cases of 

 endocarditis following influenza. 



Davis t found the influenza bacillus in the respiratory passages of a 

 large number of patients suffering from whooping-cough. 



* "Path.Soc. of London," "Brit. Med. Jour.," April 22, 1905. 

 t "Jour. Infectious Diseases," 1906, in, i. 



