678 COLLECTED STUDIES IN IMMUNITY. 



vivo. Since, however, the relations existing between toxin and its 

 antitoxin are strictly specific (tetanus antitoxin neutralizes only 

 tetanus poison, diphtheria serum only diphtheria poison, snake 

 antivennin only snake venom, etc., etc.) it is necessary to assume 

 that a chemical union occurs between the two opposing substances. 

 In view of the strict specificity this binding is best explained by 

 assuming the existence of two groups having a definite configura- 

 tion, of two groups fitting one another like a lock to a key, to use 

 Emil Fischer's apt comparison. Considering the firmness of the 

 union on the one hand, and the fact that neutralization takes place 

 even in very high dilutions without the aid of chemical agents, we 

 must assume that the binding is due to a close chemical relationship, 

 in all probability analogous to a true chemical synthesis. 



Recent investigations, in fact, have shown that it is possible, by 

 chemical interference, to disrupt the combination, to split the toxin- 

 antitoxin union into its components. Morgenroth, for example, has 

 shown this with a number of poisons. Thus with snake venom and 

 diphtheria poiosn he found that the action of hydrochloric acid 

 caused the toxin-antitoxin combination to resolve into its original 

 components, just as in pure chemistry stable combinations such as 

 the glucosides, when acted on by acids, are resolved into their two 

 components, sugar and the constituent aromatic group. These 

 investigations showed that the more stable group of the toxin 

 molecule, the group to which I have given the name " haptophore," 

 is able to exhibit marked chemical activity of specific character, 

 and it was therefore very natural to assume that just this group 

 effected the anchoring of the toxin to the cell. We see, for example, 

 how many species of bacterial poisons take weeks before they pro- 

 duce disturbances, and how they confine their injurious action to 

 heart, kidney, or nerve. We see animals ill of tetanus infection 

 exhibiting spasms and contractures for months. All this compels 

 us to admit that these phenomena can only be caused by the anchor- 

 ing of the poison by certain definite cell complexes. 



I therefore assumed that tetanus poison, for example, united 

 with certain definite chemical groups of the cell protoplasm, partic- 

 ularly of the protoplasm of the motor ganglion cells, and I further 

 believed that this chemical union was the prerequisite and the cause 

 of the disease. These groups I termed "poison receptors/' or simply 

 " receptors." Wassermann, through his well-known experiments, 

 was able to demonstrate the correctness of this view, by showing 



