Mixed Infections 85 



In experimental investigations this fact is not infrequently 

 forgotten, and it is often remarked with surprise that the 

 results of inoculation with pure cultures of a bacterium may 

 be clinically different from those observed under natural 

 conditions. 



The tetanus bacillus, which endures with difficulty the 

 effects of uncombined oxygen, flourishes in association with 

 saprophytic organisms by which the oxygen is absorbed. 

 The same thing is probably true of other obligatory anaerobic 

 organisms. 



The metabolic products of one species may intensify or 

 accelerate the action of those of an associated species, or 

 the reverse may be true and the products of different organ- 

 isms, having different chemical composition, may neutralize 

 one another, or* combine to form some entirely new sub- 

 stance which is entirely different from its antecedents. 

 Such conditions cannot fail to influence the animal infected. 



