INFECTION AND IMMUNITY 353 



to absorb its customary nutrient molecular groups, 

 which are interfered with by the presence of the toxin 

 molecules, which, though adapted for combination with 

 the receptors, are of no use to the cell. To prevent star- 

 vation the cell is supposed by Weigert and Ehrlich to 

 compensate by the regenerative formation of additional 

 receptors to meet the emergency. 



The period of "reaction" following the injection of 

 the antigen corresponds to the time during which the 

 cells are thus overcoming the embarrassment and provid- 

 ing themselves with the needed receptors. As the in- 

 jections of the antigen are repeated and the doses in- 



FIGS. 133 AND 134. 



creased, the number of new receptors to be formed 

 becomes greater and greater, and the habit of regen- 

 erating them so effectually established that they form in 

 excess of all requirements, and being superfluous detach 

 from the cell and occur free in the lymph and blood. 

 These free receptors retain their haptophilic affinity and 

 their haptophorous adaptation, so that should adapted 

 haptophiles be present they combine with them in the 

 blood, before they are able to reach the cells, or being 

 present in the drawn blood confer upon it the future 

 power of combining with the toxin molecules rendering 

 the toxin inert when injected, after the combinations 

 have been effected, into some new animal. 

 23 



