160 A MANUAL OF BACTERIOLOGY 



animal, no tetanus is produced, because by this time the 

 combination, previously a loose one, has become so stable 

 that the substances can no longer be dissociated. This 

 union can be hastened by employing more tetanus anti- 

 toxin, 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 consider- 

 able practical value in serum therapy. 



The above considerations are of importance in the antitoxin 

 treatment of disease. Antitoxin, in the strict sense, is not anti- 

 microbic, and therefore antiseptic treatment of the throat in 

 diphtheria, and of the wound in tetanus, should be pursued. 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, there- 

 fore, 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 fresh amounts of toxin that may be absorbed. 

 Hence the necessity for early treatment. Toxin already anchored 

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

 sociated 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 introduction of the 

 toxin and of the antitoxin increases ; hence the necessity for the 

 use of antitoxin in large excess. Probably the union between tissue 

 and toxin at first is 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 administration 

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



