THE PARTIAL-FUNCTIONS OF CELLS. 679 



that normal brain substance is able to neutralize definite quantities 

 of tetanus toxin. A number of objections were made against these 

 experiments, but they proved to carry no weight. I am convinced 

 that it has been proven conclusively that the cells contain definite 

 chemical groups which bind the poison. And that these groups, 

 receptors, react with the haptophore portion of the toxin, is shown 

 by the fact that it is possible to immunize with toxoids, in which, 

 of course, only the haptophore group is present. We know that this 

 haptophore group of the toxins must possess a peculiar, highly 

 complex stereochemical structure, and since it reacts in exactly the 

 same manner both with the antitoxin and with the cell receptors, we 

 conclude that the group contained in the protoplasm, the cell receptor, 

 must be identical with the "antitoxin" present in solution in the 

 scrum of the immunized animals. In view of the fact that the cell 

 receptor constitutes the preformed element, while the artificially 

 produced antitoxin represents the result, i. e., the secondary element, 

 it is most natural to believe that the antitoxin is nothing else than 

 thrust-off constituents of the cell, in fact surplus receptors which 

 have been thrust off. The explanation for this is veiy simple. It 

 is merely necessary to assume that the various specific cell receptors 

 which bind, for example, snake vemon, diphtheria poison, tetanus 

 poison, botulism poison, etc., are not intended to serve as poison 

 catchers for poisons with which the animal perhaps never comes into 

 contact under ordinary conditions, but that they are really designed 

 to chemically bind normal metabolic products, i. e., that they are 

 intended primarily to effect assimilation. These receptors are there-, 

 fore to be thought of as side chains of the protoplasm possessing the 

 power of assimilation. When laid hold of by a toxin molecule, the 

 particular normal function of this group is lost, put out of action. 

 Thereupon, following the principle discovered by Weigert, the pro- 

 toplasm not only renairs the injury, but even over-compensates the 

 defect, i. e., there is superregeneration. Finally, with the accumu- 

 lation and repetition of the injections, so many of these regenerated 

 groups are formed in the body of the cell that they hinder, as it 

 were, the normal cell functions, whereupon the cell rids itself of the 

 burden by thrusting the groups off into the blood. 



The most striking thing about this process is the enormous 

 difference between the amount of poison injected and the antitoxin 

 produced. Some idea of this disproportion can be gained from the 

 statement made by Knorr that one part of toxin produces a quantity 



