36 CHEMICAL PRODUCTS OF BACTERIA. 



bator. The ;8-prototoxin is much more stable, but gradually de- 

 composes and is converted into a toxoid when the culture is kept 

 for several months. The /3-modification of the deuterotoxin is under 

 certain conditions quite stable. These facts explain the observation, 

 previously reported, that old cultures of diphtheria gradually de- 

 crease in toxicity until a certain minimum degree is reached, after 

 which there is no further decrease. 



6. Avidity for combining with antitoxins does not suffer the 

 least change on the conversion of a toxin into a toxoid ; for instance, 

 the toxoid of prototoxin combines with antitoxin as readily as does 

 the prototoxin itself. 



7. Those varieties of poisons which combine less vigorously with 

 antitoxins are neutralized by the same reagent less promptly ; this 

 explains the observation that certain poisons of the tetanus series 

 (tetanolysin and tetanospasmin) are neutralized promptly by anti- 

 toxin only in concentrated solution. 



8. The facts observed in the experiments made upon animals with 

 toxins and antitoxins are best explained on the supposition that the 

 toxic molecule contains two independent groups of atoms, one of 

 which may be designated as the haptophorous and the other as the 

 toxophorous group. It is by the action of the haptophorous group 

 that compounds are formed with antitoxins, while the poisonous 

 action is due to the toxophorous group. The toxons also possess 

 these two groups and in these bodies the haptophorous groups are 

 identical with those of the toxins, while the toxophorous groups are 

 much more feeble in their effects. 



9. The effects of the haptophorous and the toxophorous groups can 

 in certain cases be experimentally distinguished ; for instance, Mor- 

 genroth found that when frogs were kept in the cold and successively 

 injected with toxin and antitoxin, these animals showed no evidences 

 of the disease, although the tetanus poison could be detected in their 

 nerves. On the other hand, when frogs were treated at like inter- 

 vals with toxin and antitoxin and kept in an incubator, they suc- 

 cumbed to tetanus even when all of the poison in the blood was com- 

 bined with antitoxin and an excess of the latter was present. This 

 indicates that the haptophorous group combined with the cells in the 

 cold, while the toxophorous group manifested its effects only when 

 the animal was kept in a warm place. The difference in time 

 required for the action of these two groups possibly explains the in- 

 cubation period which is observed in all cases of poisoning with bac- 

 terial toxins ; for Donitz has shown that the tetanus poison com- 

 bines almost instantaneously with the nerve cells. 



10. The toxophorous group is more complicated in structure and 

 therefore less stable than the haptophorous. The relative lability 

 of the toxophorous group and the stability of the haptophorous group 

 explain the quantitative conversion of toxins into toxoids. In a 



