12 IMMUNE SERA 



announced that similar reactions could be obtained 

 if extracts of normal organs were used as antigens. 

 Further work soon established the fact that, although 

 the reaction could no longer be considered as due 

 to a specific combination of antigen and anti- 

 body, it was, nevertheless, specific when regarded 

 as to its accuracy in detecting syphilitic infections. 



It has since been found that antigens made from 

 cultures of the spirochasta pallida do not give specific 

 reactions, for they react also with sera from patients 

 infected with other organisms of the spirochaeta 

 group. 



The Wassermann Reaction. The theory of the 

 reaction and the preparation of reagents is given in 

 detail even at the risk of repeating some of the 

 statements made above when considering the nature 

 and mode of action of bacteriolysins and haemo- 

 lysins. 



When certain bacteria or certain cells are intro- 

 duced into the tissues or into the blood stream of a 

 susceptible animal, the animal reacts and endeavors 

 to protect itself against the substances introduced. 

 After a suitable interval the blood of the inoculated 

 animal will have acquired a property which it did 

 not normally possess. The serum will be found to 

 contain anti-substances for the bacteria or cells in- 

 jected and the animal is said to be immunized. 

 These anti-substances are able to combine with 

 bacteria or cells of the type introduced. By properly 



