Influenza 



In the immunization experiments of Delius and Kolle* 

 one-twentieth of a twenty-four-hour-old culture was fatal in 

 twenty-four hours. They found that the toxicity of the cul- 

 ture does not depend upon a soluble toxin, but upon an intra- 

 cellular toxin. The outcome of the researches, which were 

 made most painstakingly, was total failure to produce experi- 

 mental immunity. 



Increasing doses of the cultures, injected into the perito- 

 neal cavity, enabled the animals to resist more than a fatal 



Fig. 1 68. Bacillus of influenza; cover-glass preparation of sputum 

 from a case of influenza, showing the bacilli in leukocytes. Highly 

 magnified (Pfeiffer). 



dose, but never enabled them to maintain vitality when large 

 doses of living cultures were administered. This observation 

 is in exact harmony with the familiar clinical observation 

 that, instead of an individual remaining immune after an 

 attack of influenza, he is quite as susceptible as before. 



A. Catanni, Jr.,f trephined rabbits and injected influenza 

 toxin into their brains, at the same time trephining control 

 animals, into some of whose brains he injected water. The 

 animals receiving 0.5 to i mg. of the living culture died in 



* "Zeitschrift fur Hygiene," etc., Bd. xxiv, 1897, Heft 2. 

 t Ibid., Bd. xxm, 1896. 



