58 



fourth did not. were all identical as regards agglutination 

 and absorption of agglutinin. 



Pfeiffer's Bacillus and Influenza. 



An account has now been given of the most important 

 observations concerning the occurrence and „internal classi- 

 fication" of Pfeiffer's bacilli, so that we are in a position to 

 discuss the views arising out of this knowledge, about the 

 relation of Pfeiffer's bacillus to influenza. 



It is the current opinion that the most convincing proof of 

 the etiological significance of a bacterium in a disease con- 

 sists in the possibility of producing that disease by the inocu- 

 lation of a pure culture of the said organism. In the case of 

 Pfeiffer's bacillus there are facts which apparently fulfil this 

 condition, viz. a laboratory infection which Kretz was the victim 

 of (see Tedesko), and Blake & Cecil's experiments. By the 

 inoculation of Pfeiffer's bacilli, the virulence of which had pre- 

 viously been enhanced by passage through 11 mice and 13 

 monkeys, in the nose and mouth of 12 monkeys the last- 

 named authors produced in each case a disease bearing symp- 

 toms quite similar to those of influenza and which distinguished 

 itself from infections due to Streptococcus and Pneumococcus, 

 among other things, by its marked effect upon the general 

 condition. 



But as Blake & Cecil admit, it is not possible to decide 

 with certainty whether such an infection is identical with 

 pandemic influenza in man, since experience obtained from 

 human pathology has clearly shown that it is impossible to 

 define the limits of the term influenza alone by the sympto- 

 matology of the individual case . 



Inoculation of pure cultures of Pfeiffer's bacillus in the 

 nose, throat etc. of man has not in the majority of cases pro- 

 duced symptoms of disease (Waul, White, & Lyall, Bloom- 

 field, Rosenau and others). In a number of cases however 

 it has been possible to call forth a catarrhal infection with 

 symptoms more or less like influenza (Davis; Cecil & Steffen). 



It may also be mentioned that the inoculation in small 

 animals particularly guinea-pigs, produces a marked hypcrac- 



