42 



demonstrate the bacilli in the blood in large quantities. (Can- 

 tani, Slatineano, Davis (1), Malone (1), Okawaha & others). 



As regards the cause of these divergent results we can 

 naturally think of different possibilities, but it must be establis- 

 hed that we cannot conclude directly, from the fact that a 

 bacillus can be cultivated from the blood after inoculation 

 of a mouse or guinea-pig, that it is different from 1 Pfeiffer's 

 bacillus. 



Virulence, a term' which principally evokes the conceptiou 

 of the power to multiply in the animal organism, is, as is 

 well known, a character which is capable of undergoing great 

 variations in the same bacterial strain. In consequence it is 

 very difficult to employ it as a basis for a classification of 

 bacteria when they do not possess a particularly well-marked 

 and constant degree of virulence. 



Tho what degree the virulence of individual strains of 

 haemoglobinophilic bacteria can vary, and especially how 

 greatly it may diminish after quite a few subcultures on arti- 

 ficial media, and what other difficulties there may be in the 

 investigation of the virulence of these bacteria as well as in- 

 dividual differences in the susceptibility of the animals, is 

 dealt with in the works of Cantani (2), Umeno & others, 

 Tanaka, Yabe, Wolf, and Blake & Cecil. 



The author who has been most emphatic that haemoglo- 

 binophilic bacteria which are the cause of meningitis and 

 septicaemic infections, must be distinguished from Pfeiffer's 

 bacillus, is Cohen, who found such bacteria in pure culture 

 in meningitis in 3 children and also cultivated them from 

 the blood. He found they were very virulent for rabbits and 

 guinea-pigs, and laid particular stress on the fact that they 

 produced a fatal septicaemia on intravenous injection into 

 rabbits. 



From several other authors* works it appears that haemo- 

 globinophilic bacteria which are the cause of meningitis can 

 usually be demonstrated in the blood of patients, and also 

 in the blood of animals injected with them 1 much more often 

 than the „ordinary" Pfeiffer's bacilli. 



It is not the intention here to proceed further with the 

 complete literature on meningitis and septico-pynemja produced 



