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1. Pfeiffer's bacillus has been constantly present 

 since its discovery, fairly widely disseminated in different re- 

 gions of the world. 



2. But the occurrence has not been uniform. 

 In the period between the two pandemics there have been 

 places where for several years it has either not existed at all 

 or at any rate was present in such small numbers that it 

 was impossible to demonstrate it even with adequate technique. 



3. The diseases in which it has been found 

 are: first of all whooping-cough, measles, and „influenza"; then 

 in a number of other infections which attack the respiratory 

 organs and the mucous membranes of the upper air-passages: 

 lung tuberculosis, pneumonia, bronchitis, bronchiectasis, angina, 

 scarlatina, diphtheria: affections of the accessory sinuses, otitis, 

 conjunctivitis. 



4. In some ,,i n f 1 u e n z a" epidemics it is met with almost 

 constantly, in others only in a minority of the cases, and 

 again in others it is absent. There are probably all possible 

 stages from constant presence to entire absence. 

 No regular relation can be shown to exist between the clinical 

 and epidemiological characters of an epidemic, and the pre- 

 sence or absence of Pfeiffer's bacillus. 



5. In a number of the above-mentioned diseases as well 

 as in healthy persons it occurs particularly in connection 

 with pandemic or epidemic „influenz a", but also 

 occurs very extensively without any direct relation 

 to epidemics resembling influenza. 



6. Pfeiffer's bacillus sometimes functions as a harmless 

 s a p r o p h y t e, at other times it reveals pathogenic qua- 

 lities in a more or less marked degree. The latter has 

 not only been the case in „influenza" but just as much in various 

 other diseases. 



7. In several preliminary epidemics to the pan- 

 demic of 1918—20 it occurred with much the same distribution 

 as it reached later in the pandemic. 



8. During the pandemic Pfeiffer's bacillus was found 

 practically constantly in certain areas and at certain times 

 with suitable choice of material, either in pure culture or in 

 overwhelming numbers, therefore under conditions very closely 

 corresponding to Pfeiffer's description in the earlier pande- 



