352 INFECTION AND IMMUNITY. 



ess the amboceptor through its cytophilous hapto- 

 phore first unites with the cell, and as a result 

 acquires an increased affinity for complement, 

 with which it unites through its complemento- 

 philous haptophore. Only after this double union 

 is completed may complement affect the cell. 

 From this it follows that complement in the cyto- 

 lytic process does not combine with the cell di- 

 rectly. As previously stated, Bordet and others 

 oppose the idea that the absorption of these bodies 

 is of a chemical nature, considering it rather to be 

 a physical process. 



Ehrlich has intimated his belief that tissue am- 

 boceptors play the chief role in the fixation of 

 foods by the cells of the body. 



2. The chemical theory explains the specificity 

 which characterizes the formation and action of 

 antibodies. Every antigen has a haptophore which 

 is different from those of other antigens; conse- 

 quently, it unites only with the corresponding cell 

 receptor, and the latter when overproduced and 

 cast into the circulation retains its specific binding 

 power for the corresponding antigen. 



3. The multitude of antibodies which have been 

 obtained indicate that the cells contain a vast 

 number of different receptors which correspond to 

 the three types now recognized; that is, there is a 

 different antitoxin receptor for every kind of 

 toxin, etc. 



4. Ehrlich has limited the application of the 

 term toxin to those substances of animal or plant 

 origin, immunization with which causes the forma- 

 tion of specific antitoxins. Other characteristics 

 have been given in Chapter XI. 



