TOXINS AND ANTITOXINS 2(57 



or radicle, while COOH and OH are side chains by means of which 

 a variety of other substances may be brought into relation with the 

 "radicle," for instance, as in methyl salicylate. 



OH 



C0 2 CH 3 



Just as nutritious substances are thus brought into workable 

 relation with the cell by means of the atom-groups corresponding 

 to side chains, so Ehrlich believes toxins exert their deleterious 

 action only because the cells possess side chains by means of which 

 the toxin can be chemically bound. These side chains, Ehrlich in 

 his later work calls "receptors." The receptors or side chains 

 present in the cells and possessing by chance specific affinity for a 



Toxin. 

 Antitoxin 



fWWIff- 



FIG. 31. TOXIN AND ANTITOXIN. 



given toxin, are, by their union with toxin, rendered useless for 

 their normal physiological function. By the normal reparative 

 mechanism of the body these receptors are probably cast off and 

 regenerated. Regenerative processes of the body, however, do not, 

 as a rule, stop at simple replacement of lost elements, but, according 

 to the hypothesis of Weigert, 24 usually tend to overcompensation. 

 The receptors eliminated by toxin absorption are not, therefore, 

 simply reproduced in the same quantity in which they are lost, but 

 are reproduced in excess of the simple^ physiological needs of 

 the cell. Continuous and increasing dosage with the poison, conse- 

 quently, soon leads to such excessive production of the par- 

 ticular receptive atom-groups that the cells involved in the 



24 Weigert, Verhandl. d. Ges. Deutsch. Naturf . u. Aerzte, Frankfurt, 189G. 



