SUGAR IK THE NUTRIENT MEDIUM. 165 



with an antagonistic action upon the cells of the 

 body analogous to the action of atropine against 

 morphine, except that the antisubstances possess a 

 minimum toxicity or none at all. The proof that an 

 ineffective mixture of toxin and antitoxin still contains 

 a virus is furnished, for example, by the fact that 

 guinea-pigs, upon whom antitoxin has less protective 

 action than upon mice, can be poisoned with mixtures 

 of toxin and antitoxin, which are entirely devoid of 

 effect on mice (Buchner). 



While the "antisubstances" of diphtheria protect 

 very well against the diphtheria virus, they have no 

 injurious effect on the diphtheria bacilli either in 

 vitro or in vivo, i.e., they are not bactericidal. The 

 diphtheria bacilli may grow in the interior of an im- 

 munized organism but they are not harmful. 



Entirely different in principle is the mode of action 

 of the "antisubstances" in cholera. Here they are 

 exquisitely bactericidal, but do not protect against 

 large amounts of the cholera virus (K. Pfeiffer). Ac- 

 cording to Emmerich, this is also true of hog ery- 

 sipelas and pneumonia. 



Much attention has been devoted to the question 

 of the specific action of the "antisubstances." Kich- 

 ard Pfeiffer, the strongest advocate of their absolutely 

 specific action, has defended successfully the follow- 

 ing standpoint in regard to the cholera vibrio and its 

 allies : Every pathogenic organism furnishes, in the 

 body of the actively immunized animal, "antisub- 

 stances" which exert a bactericidal action (often ex- 

 tremely pronounced) only against the organism in 

 question but not against its closest allies. This spe- 

 cific action is so pronounced that Pfeiffer regards 



