132 Immunity 



first in their ability to produce antibodies in the bodies of 

 animals into which they are injected; second, the mani- 

 festation of poisonous action only after a definite incubation 

 period, and, third, an extremely labile composition, by which 

 the toxin becomes quickly transformed to toxoids. 



A study of the physiological action of toxins upon the cells 

 resulted in showing that certain definite specific affinities 

 existed, and that the union of the toxin with the cell ante- 

 dated the production of symptoms. In some cases it was 

 even found possible to disconnect the anchored toxin by 

 bringing to the cells haptophorous groups for which the 

 haptophorous elements of the toxin molecule were known 

 to have an active affinity. Donitz determined the quantity 

 of tetanus antitoxin which, injected into the circulating 

 blood immediately after the toxin, absolutely neutralized 



tlsptophiLe Toxofrhlle Uaptofrhore Toxofihore 



group. group. group, gup. t 



\ 

 \ 



Ce 



Fig. 19. Diagram to represent the combining groups of the cell and 

 of the toxin respectively (after Ehrlich) (Hewlett). 



it and rendered all of the circulating toxin innocuous. If the 

 same quantity of antitoxin was given seven or eight minutes 

 after the injection of the toxin, death occurred from tetanus, 

 exactly as if no antitoxin had been given. Evidently the 

 toxin had anchored itself to the nerve-cells too quickly for 

 the antitoxin to reach and combine with it. Heymans found 

 that if an animal was injected with tetanus toxin, and its 

 entire blood withdrawn immediately afterward and replaced 

 by transfusion, it died of typical tetanus because in the brief 

 interval between the toxin injection and the transfusion, the 

 toxin molecules became anchored to the cell. 



The ability of the cells thus to anchor the toxin is supposed 

 by Ehrlich to depend upon the existence of haptophorous 

 combining affinities, which he describes as receptors. He 

 views the mode of toxin reception as depending upon a 



