532 MICRO-ORGANISMS AND DISEASE [chap. 



Bouchard, Charrin, Woodhead and C. ^Vood have shown 

 that there exists a strong antagonism between the bacillus 

 pyocyaneus or its products and the bacillus anthracis ; so 

 much so that upon the injection of the former, simultaneously 

 with or immediately after the latter, into an animal susceptible 

 to anthrax, this latter disease does not take place at all, 

 whereas a control animal not treated with the pyocyaneus 

 succumbs to anthrax. 



It is well known that certain infectious diseases, of which 

 infection occurred simultaneously in the same body, do not 

 take place simultaneously, but that the one probably has to 

 wait, as it were, till the other has gone through its course. 

 In other cases one disease has clearly an inimical influence 

 on another. Take, for instance, the observations repeatedly 

 made by surgeons that erysipelas has a curative influence on 

 certain tumours ; Fehleisen had by direct experiment with 

 pure cultures of streptococcus erysipelatos proved that certain 

 sarcomata can be made to disappear and a cure effected by 

 producing erysipelas in the skin of the part. 



But there is a converse side to this, namely the question 

 whether, and if so, to what extent, one condition, one species of 

 bacteria or its products, enhances the power of multiplication 

 and the action of another. Monti {Ac. d. Line, October 6, 

 1889) pointed out that the culture of the diplococcus pneu- 

 moniae — which, as is well known, gradually (by age and by 

 continued subcultures) loses its virulent action on animals — 

 regains the virulence if injected simultaneously with broth 

 culture of the common saprophyte proteus vulgaris, from 

 which the bacilli themselves are previously removed or killed 

 by heat. This increased virulence of the pneumococcus may 

 be achieved either by injecting this and the proteus culture 

 at the same place, or at distant places simultaneously or soon 

 after one another. Similarly I found that cultures of strepto- 



