214, MICROBES AND TOXINS 



toxic molecules ; the cell, deprived of the use of these 

 receptors, has its functional activity diminished and its nutrition 

 threatened. But all injured protoplasm possesses a reparative 

 or regenerative power ; the cell reproduces receptors ; it even 

 manufactures a great many more than is necessary. To follow 

 Weigert's dictum the living matter overstimulated by the lesion 

 regenerates itself much beyond its needs ; these receptors 

 regenerated in excess are cast off by the cell and pass into the 

 body-fluids ; and it is these which fix and neutralize a fresh 

 dose of toxin injected into the body. 



Antitoxin is nothing but these Free Receptors. — 

 It acts like a lightning-conductor. Withdrawn from the body 

 which produces it and introduced into another animal, it 

 retains the same fixing property and is the active agent in 

 therapeutic sera. 



Thus there is no essential difference between the receptors 

 which produce the antitoxin and the normal "nutrition 



S'O*):! 



Fig. 70.— Diagrams to represent Ehrlich's theory. 



1. Haptophore group h and toxophore group t. 



2. Cell C injured at / : its receptor r. The toxin is represented by T 

 with its haptophore group h and its toxophore group t. 



3. A toxin molecule : haptophore group h : toxophore group t : anti- 

 body or free receptor a. r. 



4. A cell C with a fixed receptor r : a detached free receptor forming 

 the antibody a. r. : the toxin T with its haptophore and toxophore groups 

 k and t. 



receptors " of the cell. A cell susceptible to the poison pro- 

 duces an antidote, but the antidote may also be produced by 

 cells which are insusceptible, i.e., not only by the " noble " 

 cells, but also by the connective-tissue cells, and it is necessary 



