41 



which it can only gain access by way of the blood-stream 1 in 

 so far -as it was secondary to its presence in the respiratory 

 tract. But .we have left untouched the rather voluminous lite- 

 rature on haemoglobinophilic bacteria as the cause of menin- 

 gitis and septicaemic or pyaemic infections. The reason for 

 this is that several authors have considered that organisms found 

 under such conditions, — or, generally, those that can be 

 cultivated from the blood — should not be regarded as Pfeif- 

 fer's bacilli, because it ought to be one of the characteristic 

 points of recognition of Pfeiffer's bacillus, that it is speedily 

 destroyed when it enters the blood-stream. 



In order to adjudicate upon this question we must first 

 consider some experiences of the pathogenicity of Pfeiffer's 

 bacillus for animals. 



Even in the early days of his fundamental work Pfeiffer 

 (2) reported that he could never cultivate his bacillus from the 

 blood of influenza patients. It is true that post mortem' it 

 could in some cases be cultivated from 1 spleen and kidneys 

 but was only present in very small numbers. In over 100 

 inoculation experiments in rabbits carried out in various ways 

 he observed a marked toxic action but no occurrence in the 

 blood or multiplication in the organism 1 ; on the contrary the 

 bacilli died rapidly. 



Delius & Kolle found that after intraperitoneal inocula- 

 tion into rabbits, guinea-pigs, and mice, Pfeiffer's bacillus can 

 easily increase in numbers at that site, while from the blood 

 and the different organs isolated colonies at most, could be 

 cultivated. On introduction into the blood or subcutaneous 

 tissue the majority of the bacilli were quickly destroyed. Spoo- 

 ner, Scott, & Heath. Gosio & Missiroli, Wolf and others 

 had the same experience. 



Several authors (Kamen (2), Jacorson, Saathoff), by inocu- 

 lating Pfeiffer's bacillus together with certain other bacteria 

 (alive or dead), could increase its virulence so that it could 

 easily be cultivated from the heart blood. 



But also by inoculation (especially into the peritoneal cavity 

 of the mouse or guinea-pig) of pure cultures of Pfeiffer's ba- 

 cillus cultivated from the respiratory tract in influenza, 

 whooping-cough, tuberculosis etc., many authors have been able 

 to produce a septicaemic infection or at any rate they could 



