The "Lateral-Chain Theory" of Immunity 117 



"If the cells of these organs [organs essential to life] lack 

 side-chains fitted to unite with them, the toxophore group 

 cannot become fixed to the cell, which therefore suffers no 

 injury, i. <?., the organism is naturally immune. One of the 

 most important forms of natural immunity is based upon 

 the circumstance that in certain animals the organs essen- 

 tial to life are lacking in those haptophore groups which 

 seize upon definite toxins. If, for example, the ptomaine 

 occurring in sausages, which for man, monkeys, and rabbits 

 is toxic in excessively minute doses, is for the dog harm- 

 less in quite large quantities, this is because the binding 

 haptophore groups being wanting, the ptomaine cannot, 

 in the dog, enter into direct relation with organs essential 

 to life." . . . "The haptophore group exercises its 

 activity immediately after injection into the organism, while 



Fig. 9. Shows how the haptophores having united, the toxophores 

 find a secondary adaptation to the cell, and so can poison it (after 

 Ehrlich) (Hewlett). 



in all toxins with the perhaps solitary exception of snake- 

 venom the toxophore group comes into activity after the 

 lapse of a longer or shorter incubation period which may, 

 e. g., in the case of diphtheria toxin, extend to several weeks." 

 "The theory above developed allows of an easy and natural 

 explanation of the origin of antitoxins. In keeping with 

 what has already been said, the first stage in the toxin 

 action must be regarded as the union of the toxin by means 

 of its haptophore group to certain 'side-chains' of the cell 

 protoplasm. This union is, as animal experiments with a 

 great number of toxins show, a firm and enduring one. The 

 side-chain involved, so long as the union lasts, cannot exer- 

 cise its normal nutritive physiological function the taking 

 up of food-stuffs. It is, as it were, shut out from participat- 

 ing, in the physiological sense, in the life of the cell. We 



