ANTITOXINS AND RELATED ANTIBODIES 



135 



it is inferred, therefore, that they are similarly constituted. Further 

 light is needed on this subject. 



Diagrammatic Representation of Toxin and Antitoxins. The 

 preceding facts may in large part be recorded by diagrams. These 

 are, of course, arbitrary in shape and appearance, but are helpful 

 in an understanding of the reaction. The diagrams commonly 

 used for this purpose are given in Fig. 65. 



Preferential Union of Toxins with Body-cells. The union of 

 antitoxin with toxin occurs apparently as readily within the 



A. 5. 



Fig. 65. Diagrammatic representation of toxins and of antitoxin pro- 

 duction 1, Toxin molecule: a, Haptophore; 6, toxophore. 2. Toxoid, a 

 toxin molecule that has lost its toxophore. 3, Molecule of cell protoplasm 

 showing the union of the toxin molecule: a, Free toxin; 6, toxin attached to 

 a cell receptor c; d, other cell receptors. 4 illustrates the overproduction of 

 receptors by the cell and their elimination (6) into the blood-stream as anti- 

 toxin molecules (c). 5, Neutralization or union of antitoxin with toxoid 

 and toxin. 



body as without. When toxins are injected and antitoxins are 

 present in the circulation, the latter will commonly unite with 

 the former and prevent union with the body-cells. In some 

 exceptional conditions, however, this is shown not to occur; for 

 some reason the affinity of cell receptors still united to the cell 

 seems to be greater than those free (antitoxin). In other words, 

 the tissues seem to become hypersensitive to the presence of the 

 toxin, so that the antitoxin no longer protects. Tissue immunity 



