ANTITOXIN TREATMENT 189 



combination between toxin and antitoxin, previously a 

 loose one, has become so stable that it can no longer be 

 dissociated. This union can be hastened by employing 

 more tetanus antitoxin, for with an excess of antitoxin, 

 even after only half an hour, it is impossible by means of 

 adrenalin to free the tetanus toxin. This experiment, 

 therefore, shows that the combination of tetanus toxin 

 with antitoxin takes place slowly and is at first a loose 

 one, and that the union becomes firmer and firmer 

 with lapse of time. It also suggests the possibility of 

 hastening the combination by increasing the amount of 

 antitoxin a point of considerable practical value in serum 

 therapy. 



The above considerations are of importance in the antitoxin 

 treatment of disease. The fact that the toxophore group of the 

 toxin does not come into action as a rule for many hours at least 

 (an exception is snake- venom) is a fortunate coincidence, for the 

 antitoxin may, therefore, act before tissue damage has occurred. 

 Antitoxin cannot repair tissue damage if this has been produced 

 by the toxin, but it can, and does, prevent the occurrence of 

 further damage by neutralising any toxin that may be present. 

 Hence the necessity for early treatment. Toxin already anchored 

 to the tissues by its haptophore group may for some time be 

 dissociated from them if a multiple of the simple neutralising 

 dose of antitoxin be injected, and the quantity necessary to 

 accomplish this rises rapidly as the interval between the introduc- 

 tion of the toxin and of the antitoxin increases ; hence the neces- 

 sity for the use of antitoxin in large excess. Probably the union 

 between tissue and toxin is at first a loose one, and a large 

 amount of antitoxin by mass action transfers the affinity of the 

 toxin from the tissues to itself. It must be clearly recognised that 

 colloidal reactions (to which category that between antitoxin 

 and toxin, anti-body and antigen, belongs) differ considerably 

 from ordinary chemical reactions. 



An essential condition in antitoxic treatment is the administra- 

 tion of a sufficient amount of anti-serum, and this does not depend 

 on the actual volume of serum injected. The anti-serum may be 



