INFECTION AND IMMUNITY 351 



amboceptor not having solvent properties in itself, can 

 do nothing, though it may connect with the corpuscles. 



Great interest attaches to the source of the antibodies. 

 Undoubtedly they are of histogenetic and of cellular 

 derivation. It was orginally insisted that they were 

 derived from those cells for which the antigen had some 

 specific affinity, but this view has gradually given place 

 to the opinion that many cells participate in their 

 formation. 



A theory of antibody formation known as the lateral 

 chain theory, suggested by Ehrlich, has been extremely 

 useful in enabling the student to think clearly upon the 

 genesis and operation of the antibodies, and therefore 



FIG. 131. 



has been exceedingly popular for a decade or more. 

 The visualization given was intended to prevent the 

 student from concluding that the reactions are of 

 ordinary chemical nature. Ehrlich still inclines toward 

 this view, but many proofs have been brought forward 

 to show the true chemical nature of the processes. 



In giving a brief outline of the theory it seems best 

 to adhere to the original ideas and illustrate it by means 

 of its author's own ideograms. 



The investigations began with a study of the chemical 

 constitution of the diphtheria toxin, and it is important 

 to remember that the experiments were made with toxin 

 antigens before other antigens and antibodies were well 

 known. Ehrlich found that the diphtheria toxin was 



