22 



mic. In other cases it was met with in considerably m'ore 

 limited distribution, and lastly many observers, inclu- 

 ding some of the most noted bacteriologists, have either n o t 

 found it at all or only exceptionally. 



These negative results are undoubtedly due in many in- 

 stances to defective technique in the examination; but this is 

 certainly inadequate to account for all the negative findings. 

 It must be assumed that there are places where Pfeiffer's ba- 

 cillus has actually been absent or has played a quite subordinate 

 role during a part of the pandemic, and that as regards its 

 frequency of occurrence in patients there have existed all pos- 

 sible transitions from the most scanty to the most abundant 

 occurrence. 



9. On the whole Pfeiffer's bacillus had a considerably 

 smaller distribution during the first outburst of the pandemic 

 in the summer months of 1918 than later on. There are 

 however places where immediately after the appearance of 

 the pandemic it was found in considerable numbers in the 

 majority of the patients. On the whole it must be assumed 

 that the distribution of this microbe increased to a mar- 

 ked extent in direct relation to the first appearance of the 

 pandemic in the different countries. While, generally speaking, 

 the distribution of the bacillus extended during the course 

 of the pandemic, there were also regions where at an early 

 date it was widespread and during the further course of the 

 pandemic it was encountered less frequently. 



10. Pfeiffer's bacillus occurs in influenza in intimate rela- 

 tion with the most important pathological changes and must 

 be assumed to play a decided pathogenic role. 



11. It is found essentially in the early stages of the 

 disease, afterwards disappearing or decreasing considerably in 

 the course of quite a few days. How quickly Pfeiffer's ba- 

 cillus disappears depends probably to a great extent upon the 

 other bacterial flora which may be very different in different 

 places. .■.-.«.-. irnr u 



It is found presumably (the same length of time from 

 the beginning of the disease) more frequently in uncompli- 

 cated influenza than in influenza with pneumonia, but 

 the difference is not great. 



