TETANUS ANTITOXIN 7 



into some animal, preferably a horse. This should be 

 followed by a rise of temperature, and by swelling at the 

 seat of injection. Unless this reaction is obtained no anti- 

 toxin will be formed. Gradually increasing doses of the 

 toxin must be injected from time to time, care being taken 

 to obtain a distinct reaction after each injection, and to 

 make the fresh injection before the effects of the last one 

 have completely passed away. After a time it will be found 

 that it is very difficult to obtain a local reaction, or a rise 

 of temperature, even when large quantities of toxin are 

 injected. During the whole of this period it will be found 

 that the antitoxic value of the blood is rising more or less 

 rapidly, and at last there is sufficient antitoxin present 

 to make it valuable for the treatment of diphtheria patients. 

 /The antitoxin in the serum injected into a patient suffering 

 from the effects of diphtheria poisoning, combines with the 

 toxin formed by the diphtheria bacillus, and so prevents it 

 from exerting its deleterious action upon the tissues of 

 the patient.) The diphtheria bacilli, with their poison 

 neutralised, now behave like ordinary non-pathogenetic 

 organisms, and are rapidly destroyed by the tissues, and 

 the patient recovers. The power of this antitoxic substance 

 may be realised when it is borne in mind that doses of 

 antitoxic serum containing 12,000 to 30,000 units may be 

 injected with safety into a diphtheria patient. A single 

 cubic centimetre of the serum of the treated horse may 

 contain a thousand units, each one of these units being 

 sufficient to neutralise toxin sufficient to kill, within four 

 days, one hundred half -grown guinea-pigs ; the amount of 

 neutralising and protective power thus obtained is therefore 

 enormous, and we can readily realise why the antitoxin 

 treatment of diphtheria has proved so successful. 



In tetanus the principle of production of antitoxin is the 

 same as in diphtheria, but the treatment has not been so 

 successful, because the disease in this case does not manifest 

 itself locally in the first instance, the poison has already 

 attacked the nerve centres before the necessity for treatment 

 makes its appearance. The damage has already been done, 

 and antitoxin, though it can neutralise the poison, and so 

 prevent further damage being done, cannot make good the 



