MECHANISM OF ANTIBODY FORMATION 133 



(1942) who isolated the antitoxin in crystalline form after enzymic 

 digestion of the original complex antitoxic globulin and by eliminating 

 the inactive component. 



Despite the undecisive nature of the results of the investigations 

 carried out previous to that of Northrop it might not be in vain to 

 present briefly the nature and the type of these experiments. It is to 

 be noted that because of its theoretical importance this question has 

 been an object of study by older immunologists, namely, Bordet, 

 Ehrlich, Sachs, Morgenroth, Pfeiffer, Friedberger, etc., and immunol- 

 ogists of our times, Landsteiner, Heidelberger, Marrack, and others 

 and their collaborators. 



Ehrlich and Morgenroth (1901) carried out cross immunization 

 experiments with ox, goat and rabbit blood cells, and then, with the 

 adsorption technique, they arrived at the conclusion that plural im- 

 mune bodies are produced by injections of ox and goat blood. By 

 eff^ecting differentiation of various groups of immune bodies by means 

 of the anti-immune bodies they believed they had shown the formation 

 of anti-antibodies. 



Bordet (1899) demonstrated the formation of anti-hemagglutinins 

 (anti-amboceptors). Fowl's serum injected intraperitoneally into a 

 rabbit produced an anti-immune body which protected rabbit red 

 blood corpuscles against the hemolytic action of fowl's serum. 



In a subsequent extensive study Bordet (1904) observed that red 

 blood corpuscles of diff"erent species of animals, sensitized by appro- 

 priate hemolytic sera obtained from a species B, lose their sensitivity 

 to complement when treated with the anti-amboceptor. In certain in- 

 stances it was not necessary to use for immunization the serum con- 

 taining specific amboceptor; it was sufficient to inject the animal, 

 namely the guinea pig, with normal serum of species B, which Bordet 

 stated, contains normal amboceptors. (See also Muir and Browning, 

 1906). 



Friedberger and Moreschi (1908) stated that in their earlier ex'peri- 

 ments they believed they had demonstrated the formation of anti- 

 amboceptors by immunizing goats with hemolytic immune rabbit serum 

 against goat red corpuscles. In later experiments, contrary to their 

 expectations, when the serum of a rabbit immunized with goat's serum 

 hemolytic for rabbit corpuscles was added to rabbit red corpuscles 

 sensitized wdth goat amboceptor the hemolysis in the presence of 



