6 ACTION OF ANTITOXINS 



anti-bacterial substance, a specific substance that has far 

 less power to neutralise the toxin, but far greater power 

 to destroy the bacilli. The only two true antitoxins as 

 yet brought into play in practical medicine are the diphtheria 

 antitoxin and the tetanus antitoxin, though similar sub- 

 stances are now used in the treatment of snake-bite and 

 of pneumonia, and one or two similar diseases. 



Antibacterial substances, however, now constitute a very 

 important class of therapeutic agents, the whole of the 

 vaccines, whether dead or living, being of this type. In 

 the case of the new tuberculin, the bodies of the bacilli 

 are broken down in order to allow the whole of the elements 

 contained in the body of the tubercle bacillus to come into 

 play. Typhoid vaccine, cholera vaccine, and others are 

 all of the same class. The poisons thus locked up in the 

 bacteria are sometimes spoken of as endotoxins. 



From the fact that these antitoxic substances are stored 

 up in the fluid constituents of the blood, it has been found 

 possible to produce antitoxins in one animal, and then by 

 drawing off its blood, and allowing the clot to separate from 

 the serum to obtain a fluid containing a large quantity of 

 antitoxin which, injected into a second patient, acts upon 

 the toxin, neutralising it just as surely and completely as if 

 it were acting upon the original patient. This has gradually 

 developed into a definite system of treatment the anti- 

 toxin treatment. It has been worked out most thoroughly 

 in diphtheria in the human subject, and in tetanus in veteri- 

 nary medicine ; whilst fair results have also been obtained 

 using a similar method in the treatment of snake poisoning. 

 In Diphtheria, the best results have been obtained (1) 

 because the local lesion, i.e. the false membrane, etc., is 

 usually well marked before the constitutional disturbances, 

 i.e. the toxic effects, make their appearance ; and (2) 

 because the poison is not only formed slowly, but takes some 

 time to produce its effects upon the nervous tissues to which 

 it usually attaches itself. 



To produce diphtheria antitoxin all that is necessary is 

 to inject subcutaneously the toxic products of the diphtheria 

 bacillus grown in slightly alkaline broth, or still better, in 

 broth containing a certain proportion of blood plasma, 



