INFLUENZA. 285 



influenza-bacilli in almost absolutely pure culture, and 

 always in surprising number. The bacilli usually lie in the 

 mucous ground-substance arranged in nests and groups ; 

 they are found also within the pus-corpuscles, at the begin- 

 ning of the disease in small number, and during convales- 

 cence in preponderating number. In the latter condition 

 they surround the nucleus and are not included within 

 it. Sputa containing influenza-bacilli are often ejected for 

 days and months. Especially in cases of tuberculosis have 

 such chronic complications of influenza with broncho- 

 pneumonic localization not been rare. The bacilli have 

 been found in the bronchopneumonic foci in cases of 

 influenza-pneumonia, rarely in the pus in cases of influenza- 

 empyema. Canon observed in the blood of influenza- 

 patients delicate bacilli resembling those of influenza. 

 According to Pfeiffer's investigations, these organisms, if 

 influenza-bacilli at all, are exceptional, for, as a rule, the 

 organisms are not present in the blood. 



With regard to the localisation of the bacilli in the gastric 

 and nervous forms of influenza, unequivocal investigations 

 are wanting. Likewise, the numerous complications and 

 sequelae of influenza have thus far been little studied from 

 the bacteriologic standpoint, so that it has not yet been de- 

 termined whether they represent results of the activity of 

 the influenza-bacillus or its toxin, or are secondary infec- 

 tions. In a case of influenza-aortitis Pfeififer found, in addi- 

 tion to the diplococci of Frankel, numerous influenza- 

 bacilli, and in the exudate from a case of influenza-meningitis 

 diplococci exclusively. 



The bacillus of influenza has never been found outside 

 the human body, in the earth, or in water. It could scarcely 

 persist for a long time under these conditions on account of 

 its feeble powers of resistance. 



Portals of Infection for, and Distribution of, the In- 

 fluenza-bacillus. The influenza-bacillus is probably taken 

 up by the air-passages exclusively. Its distribution by 

 means of dried and powdered sputum can play an etiologic 

 role only in restricted degree, as the bacillus withstands 

 drying so badly. The ordinary mode of conveyance is 

 certainly by means of the moist nasal and bronchial secre- 

 tions of influenza-patients. The widespread and often pan- 

 demic distribution of influenza may be explained by the fact 

 that in the first place the susceptibility of human beings to 



