24 IMMUNE SERA. 



various substances and processes one to another, 

 as all of the symptoms are referable to one organ, 

 the central nervous system. In this disease the 

 antitoxin against the tetanus poison must consist 

 of side-chains or receptors thrust into the circula- 

 tion by the cells of the central nervous system. 



toxophore group 



POISON MOLECULE 



haptophore group 

 receptor 



The action of the antitoxin then would be this, that 

 these free receptors combine with the haptophore 

 group of the tetanus poison as soon as this reaches 

 the circulation, and thus prevent this poison /from 

 combining with and injuring the cells of the central 

 nervous system. This I was able to prove experi- 

 mentally by showing (i) that the central nervous 

 system of most animals susceptible to tetanus is 

 able to combine with the tetanus poison in vitro; 



