CHAPTEE VI. 



ANTAGONISM AMONG MICROORGANISMS. 



ONE of the most recent achievements in bacteriology is the dis- 

 covery of the antagonism which exists among certain pathogenic 

 microorganisms. That such antagonism exists has been demon- 

 strated by cultivation, and inoculation experiments. 



Pawlowsky (Virchow's Archiv, B. cviii.) has furnished strong 

 experimental evidence of the antagonism which exists between the 

 pneumococcus of Friedlander and the bacillus of anthrax ; as, in 

 eight rabbits infected with a fatal dose of anthrax, all of the animals 

 were saved by a subsequent injection of a pure culture of the pueu- 

 mococcus. The same author also ascertained that the micrococcus 

 prodigiosus is also antagonistic to the coccus of erysipelas. Thus, 

 ten rabbits were first inoculated with anthrax bacilli, and then cul- 

 tivations of the micrococcus prodigiosus were injected subcuta- 

 neously into each animal on two occasions, two and twenty-four 

 hours after injection ; of these ten animals, eight recovered. He 

 also found that subcutaneous injection of anthrax bacilli, and cul- 

 tivations of pneumonococci were fatal to rabbits ; and that subcu- 

 taneous injection of cultivations of anthrax bacilli and staphylo- 

 coccus pyogenes aureus was not followed by the death of the 

 animal ; four rabbits treated with a culture of the staphylococcus 

 aureus recovered ; of seven anthracic rabbits treated by subcuta- 

 neous injection of a culture of streptococcus erysipelatosus, two 

 died. 



Emmerich (Fortschritte der Medioin, B. v. 1887) has also studied 

 experimentally the antagonism among pathogenic microbes in the 

 living organism. His experiments on rabbits have shown the 

 value of the erysipelas cocci as a protective and curative agent in 

 anthrax in these animals. In one series of experiments the rab- 

 bits were first inoculated with a large quantity of a reliable culture 

 of the streptococcus of erysipelas, and then, two to fourteen days 

 later, the animals were again inoculated with a pure culture of the 

 bacillus of anthrax. Of fifteen animals treated in this way. seven 

 recovered, while all the control animals infected with anthrax, but 

 not protected by the microbe of erysipelas, died ; of the seven 

 animals which died after inoculation of both microbes, some suc- 

 cumbed to the anthrax bacillus, and some to the microbe of ery- 



