44 



slrated in the last few years in the group of bacteria which 

 everybody agrees to call Pfeiffer's bacilli, no particular signifi- 

 cance can be attached to this. Another argument in favour of 

 not classing the meningeal strains as Pfeiffer's bacilli is that the 

 corresponding meningitis commonly arises without any con- 

 nection with influenza epidemics; and so long as Pfeiffer's 

 bacillus is credited with being the bacillus of influenza, it 

 would be difficult to class the other bacteria as influenza-ba- 

 cilli also. But with the surrender of the theory of the specific 

 importance of Pfeiffer's bacillus for influenza, this argument 

 naturally falls to the ground. 



Most authors have therefore decided to call haemOglobinb- 

 philic bacteria from meningitis and septicaemic infections 

 Pfeiffer's bacilli, when their morphological and cultural cha- 

 racters are identical with this organism even though they 

 possess a particular virulence. 



To show how untenable it is to support Cohen's sharp distinc- 

 tion, a contribution of Bender (from Pfeiffer's Institute in Breslau) 

 which has recently appeared, will be made the object of a further 

 discussion of the problem. 



Bender starts by assuming that Cohen's bacillus is different 

 from Pfeiffer's and tries to show that the haemoglobinophilic ba- 

 cillus he found in a case of meningitis is identical with the former 

 and distinct from the latter. On injecting 4 cultures, which had 

 been grown for from 6 weeks to 3 months, intravenously into 3 

 rabbits, 2 of them were unaffected while the third died 17 hours 

 after the injection. Pfeiffer's bacillus was grown in pure culture 

 from the heart blood, spleen, and liver but could not be demonstrated 

 by direct microscopic examination. ,,Angesichts der grossen injizier- 

 ten Bazillenmenge ist bier der Tod jedenfalls durch Vcrgiftung be- 

 dingl", for which reason he does not put much reliance on this 

 result but believes, in view of the other 2 rabbit experiments and 

 several other negative animal experiments, he has shown that his 

 bacillus is identical with Pfeiffer's and distinct from Cohen's. 

 But this conclusion is hardly justified. In the first place it is 

 very possible that the bacillus was originally virulent but lost that 

 property with the rather lengthy cultivation on artifical media As 

 already mentioned such a loss of virulence can take place very 

 rapidly. The bacilli with which Cohen could produce septicaemia 

 in rabbits were certainly cultivated still longer, but it is highly pro- 

 bable that the rapidity with which the virulence diminishes may be very 

 different in different cases depending amongst other things on the 

 constitution of the nutritive medium. Pfeiffer's bacillus is in fact 

 a rather fastidious organism and the conditions it is subjected to 



