84 



this microbe were certainly reported during and after the last 

 influenza pandemic, than in the preceding years, which is 

 only to be expected in view of the increased distribution of 

 Pfeiffer's bacillus and the greater attention that has been paid 

 to it. But if this form of meningitis is to be looked upon as 

 an influenza meningitis we should expect a much greater 

 augmentation of its frequency in direct relation to influenza. 

 Meningitis due to Pfeiffer's bacillus is undoubtedly much 

 more widely distributed than appears to be the case from 

 the hundred or so published cases. When the attention is 

 not specially directed to Pfeiffer's bacillus it can easily be 

 confused in the spinal fluid, with Meningococcus or Pneumo- 

 coccus, — particularly with the latter if Gram's method of 

 staining is not used. Cultivation also will often fail if the 

 spinal fluid hos to be kept for some time before inoculation. 

 By microscopic examination of the spinal fluid and exudate 

 from the surface of the brain I have in 2 cases observed 

 small Gram-negative rods which probably could be taken to be 

 Pfeiffer's bacilli, but the cultures of which did not grow. 



6. Healthy persons. 



The occurrence of Pfeiffer's bacillus was investigated in 

 2240 healthy persons, exclusively by cultivations from the throat. 



Unless otherwise mentioned, each person has visited the 

 Serum Institute so that there is no question of conveying 

 the material for inoculation from 1 another place with ihe con- 

 sequent danger of the death of Pfeiffer's bacillus before the 

 cultures were made. 



Nearly all the examinations of healthy people reported 

 from other places were made on definite groups of indi- 

 viduals, the numbers of each group having been in contact 

 with one another for a longer or shorter time (soldiers, per- 

 sonel of laboratories and hospitals etc.), so that the absence 

 or different degrees of distribution of Pfeiffer's bacillus have 

 only been demonstrated in the group examined and it is not 

 possible to draw conclusions about the occurrence of the ba- 

 cillus in the population as a whole. 



A number of my investigations of healthy persons are of 



