82 MUSGRAVE. 



its fermentative action on the medium. Klein 7 showed that bacilli of 

 the Gaertner group had an enhancing value on the virulence of B. typho- 

 sus when they were grown together with the latter in culture tubes. 



The mechanism by which the facultative aerobic spirillum of cholera, 

 acting in the anaerobic environment of the intestine, produces such 

 intense toxaemia has not been satisfactorily explained and the influence 

 which symbiotic bacteria may exert here needs to be investigated. Sev- 

 eral years ago Nageli advanced the hypothesis that cholera was the result 

 of the cooperative action of two kinds of bacteria. Experimenting 

 along this line Metchnikoff found a bacterium which greatly increasd the 

 pathogenic action of 8. cholera and Nencki has described bacteria which 

 in themselves were non virulent, but which added greatly to the virulence 

 of 8. cholera, when they were grown together. Musgrave and Clegg 

 have maintained the virulence of a strain of 8. cholera for more than 

 one year by growing it symbiotically with amoebae. The same strain 

 grown pure on artificial media lost much of its virulence during this 

 time. 



There is abundant evidence to show that the symbiosis of the diph- 

 theria bacilli and of the streptococci enhance the virulence of both or- 

 ganisms in many cases of diphtheria complicated by streptococcus infec- 

 tion. 



There are also certain bacteria and products of bacteria which are 

 antagonistic to other bacteria or diseases. Emmerich, Low 8 and others 

 have fully established an active antagonism of the products of B. pyo- 

 cyaneous for the anthrax bacillus and for several other organisms. In 

 a somewhat similar manner Rettger 9 and others have proved an antag- 

 onistic action of the products of B. prodigiosus for certain other bacteria. 

 Turro 10 found that subcutaneous injections of beer yeast would protect 

 rabbits aginst otherwise fatal inoculations of streptococci and staphy- 

 lococci. This work has also been confirmed and amplified by other ob- 

 servers. Lode " cultivated a diplococcus which possessed marked 

 antagonistic properties, toward several well-known bacteria, among them 

 staphylococci, B. anthracis, B. cholera susis, B. typhosus and the cholera 

 spirillum. This diplococcus not only had the power of destroying these 

 bacteria in cultures, but this property was also present in Berkefeld 

 filtrates of the cultures. 



''Lancet (1904), 2, 477. 



8 Emmerich and Low: Ztschr. f. Hyg. u. Infectionskrankh., Leipz. (1899), 31, 

 I; ibid. (1901), 36, 9. Emmerich: Gentrbl. f. Bakteriol. Orig. (1902), 32, 

 82. Low and Korsehun: Ibid. (1902), 31, 1. Emmerich and Trommsdorff : 

 Ibid. (1903), 33, 627. 



"J. Infect. Dis. (1905), 2, 562. 



w Gentrbl. f. Bakteriol. Orig. (1903), 34, 22. 



"Ibid. (1903). 33, 196. 



