234 ANTITOXINS 



both instances, however, as developed later, if the mixtures had been 

 allowed to stand longer, these results would not have been secured. Al- 

 though performed originally to sho*w that an antitoxin does not act by 

 actually destroying its toxin, these experiments simply demonstrate the 

 importance of the element of time in the reaction, without throwing any 

 real light upon the nature of the new toxin-antitoxin compound, if such 

 exists. 



That toxin is counteracted by antitoxin, independent of the partici- 

 pation of living tissue-cells, has been quite conclusively proved by ex- 

 periments in vitro. Ehrlich showed that the agglutinating qualities of 

 ricin a vegetable toxin may be overcome in the test-tube by adding 

 antiricin, the corresponding antitoxin. Similar results were obtained 

 by Ehrlich with tetanolysin and tetanus antitoxin, and by Stephens 

 and Myers with cobra venom and its antivenin. 



It is probable that antitoxin has a similar action when injected for 

 therapeutic purposes, as for curing an infection. The longer the in- 

 terval that has elapsed between the time of infection and the administra- 

 tion of antitoxin, the less satisfactory will be the result, as antitoxin 

 becomes less powerful when toxins have formed a firm union with the 

 body-cells. This is especially true in tetanus, where even very large 

 doses of antitoxin may be incapable of dissociating the toxin molecule 

 from the nerve-cells, the serum, therefore, being of greatest value in 

 prophylaxis. In diphtheria, however, the union between toxin and cells 

 is less firm, and the antitoxin is probably capable of neutralizing the 

 toxin already present in the cells, and especially any toxin that may 

 become dissociated from the cell or is freshly prepared by the diphtheria 

 bacillus at the site of infection. The indication, therefore, in giving 

 antitoxin, is to give a dose large enough to neutralize all free and loosely 

 bound toxin, with an excess to neutralize dissociated toxin and that pre- 

 pared by the bacillus during the course of the infection. 



The introduction of the test-tube experiment into the investigation 

 of these reactions permitted more exact observations to be made, and 

 the evidence secured by this means, as well as by carefully graded quan- 

 titative animal experiments, would seem to indicate that we should ac- 

 cept, for the present at least, the conception of the chemical nature of 

 the process. 



PRODUCTION OF ANTITOXINS FOR THERAPEUTIC PURPOSES 



Diphtheria and tetanus antitoxins are manufactured on a large 

 scale, and are used extensively in the prevention and cure of these in- 



