IMMUNITY AND ANAPHYLAXIS 83 



We have then the following facts: 



1. The toxins of tetanus and diphtheria may be injected 

 into sensitive animals in non-toxic or toxic doses and then: 



(a) Each injection of a non-toxic or slightly pathogenic 

 dose protects the injected animal after a certain incubation 

 period against a larger dose : active immunity. 



(b) The serum of the animal thus actively immunized 

 will neutralize the pathogenic action of the toxin in vitro, 

 and if injected prophylactically into a new animal will protect 

 this animal against a pathogenic dose : passive immunity. 



(c) The injection of toxic mixtures of toxins with their 

 antitoxins as well as the preventive injections of "anti" 

 sera from animals of the same species never causes ana- 

 phylactic disturbances. 



Thus for tetanus and diphtheria toxins there is active and 

 passive immunity; but there is never anaphylaxis, either active 

 or passive. 



2. Living pathogenic bacteria may be easily injected in 

 non-pathogenic doses, but in the technic of vaccinations it 

 is convenient to employ either living cultures with attenu- 

 ated virulence, -or bacterial bodies killed by heat or other 

 procedures or filtered broth cultures without bacteria. 

 The injection of all these products in non-pathogenic doses 

 provokes in part reactions of the same nature as in the 

 preceding section, that is to say: 



(a) An active anti-infectious immunity in the treated 

 animal. 



(b) The serum of the treated animal can confer a passive 

 immunity on a normal animal but at the same time this 

 same treatment has caused 



(c) A state of active anaphylaxis in the treated animal 

 and the serum of this animal has become able to transfer 

 passively anaphylaxis to a new animal. 



Thus, for all living or dead pathogenic bacteria as well 

 as for their filtered broth cultures there is at one and the 

 same time active and passive anti-infectious immunity and 

 active and passive anaphylaxis. 



3. Pathogenic albumins behave, from the point of view of 

 their immunizing or anaphylactic reactions, exactly the 



