17 



Pfeiffer's Work. 



The fact that Pfeiffer's discovery (1,2, (see also Pfeiffer 

 & Beck (1)) immediately produced such a convincing im- 

 pression depended upon the three following points: 



(1) that the „influenza-bacillus" was found with great re- 

 gularity and in extraordinary numbers, sometimes in ^absolutely 

 pure culture'", in all the typical influenza cases examined; 

 (2) that it was a hitherto completely unknown organism which 

 in addition (3) was distinguished by the characteristic, which 

 also had never previously been known, that, as already stated, 

 it could only be cultivated on media containing red blood cells 

 or dissolved haemoglobin. 



These three points formed a striking contrast to the ob- 

 servations other investigators had made in the course of the 

 pandemic; they had in fact only found already familiar orga- 

 nisms: Streptococci, Pneumococci, Staphylococci, to which, on 

 account of their general occurrence in other diseases, could 

 hardly be ascribed any specific significance in influenza, the 

 more so because some observers found principally one, while 

 other observers found principally another of the organisms 

 mentioned. As Pfeiffer's work also was carried out with 

 great capacity and presented in a clear and elegant form, 

 it is intelligible that it might evoke a feeling of relief that 

 at last we had found the solution of the problem. 



Looking at Pfeiffer's work however from the critical po- 

 sition we have reached after the later contradictory experien- 

 ces, particularly in the last pandemic, the deficiencies of his 

 proof are very evident. 



Pfeiffer had shown that his bacillus was constantly found 

 in cases of influenza he examined and occurred in such inti- 

 mate relation with the principal pathological changes that it 

 might well be the specific primary influenza microbe. But was 

 it characteristic for influenza? Was it not also present in 

 other diseases and in normal persons? 



On this question Pfeiffer (1) certainly says that „in very 

 numerous control experiments" it could not be demonstrated 

 in „ordinary bronchial catarrh, pneumonia and phthisis," but 

 more detailed information is wanting and subsequent investi- 



2 



