564 BACTERIOLOGY. 



the neutralization of such intracellular poisons as they 

 may elaborate or as may be bound up as integral por- 

 tions of their constituent protoplasm. 



Furthermore, in so far at least as induced immunity 

 is concerned, the bulk of the experimental testimony 

 supports the opinion that the reaction is specific ; that 

 is to say, be the systemic reaction evidenced as the 

 elaboration of an antedote to a soluble poison or as 

 increased facility to destroy living bacteria, it is called 

 forth only through the specific stimulus afforded by the 

 injection of the animal with the particular poison or 

 bacterium from which we desire to protect it. Thus, 

 for instance, an animal rendered immune from tetanus 

 toxin, is not immune from diphtheria toxin or from the 

 inroads of diphtheria bacilli ; similarly an animal im- 

 mune from any of the pathogenic species of bacteria is 

 immune from that species only and not necessarilv from 

 any others. 



However, the tissues and fluids of most animals are 

 endowed by nature with some degree of both general 

 antitoxic and germicidal functions though in no case is 

 this so pronounced as that seen in animals that have 

 been systematically subjected to specific treatment with 

 the view of accentuating the one or the other of these 

 functions. 



An observation of fundamental importance to the 

 question of immunity was made by R. Pfeiffer in 1895. 

 While investigating Asiatic cholera he found that 

 animals could be immunized from the specific endotoxin 

 of the organism causing that disease ; that the blood 

 serum of such immune animals when injected into 

 normal animals protected them against what would 



