ANTITOXINS 151 



formed by the injection of toxin is antitoxic and not 

 anti-microbic, and the diphtheria bacillus will grow and 

 multiply in diphtheria antitoxin. Since, however, the 

 pathogenic effects of an organism such as the diphtheria 

 or the tetanus bacillus are caused by the toxin which it 

 forms, the antitoxin will counteract the effects of the 

 micro-organism as well as of its toxin. The neutralisa- 

 tion of the micro-organism, however, may not be quite 

 complete, a certain amount of local reaction or necrosis 

 ensuing. 



Antitoxins are prepared by injecting animals prefer- 

 ably horses, but goats, rabbits, etc., may also be employed 

 with bacterial toxins or with cultures. 



With those organisms which produce potent toxins 

 such as diphtheria and tetanus, it is customary to grow 

 the organism in a fluid medium so that an active and 

 virulent toxin is obtained. The culture is then filtered 

 through a Berkefeld or Pasteur-Chamberland filter and the 

 toxic filtrate inoculated subcutaneously into an animal, 

 generally a horse, commencing with sub- lethal doses. 



The dose of toxin can be gradually increased, and con- 

 currently with the increase in insusceptibility the blood- 

 serum acquires antitoxic properties. The treatment is 

 tedious, and the activity of the antitoxic serum is largely 

 dependent upon the amount and activity of the toxin 

 injected. The requisite degree of strength having been 

 attained, the horse is bled with aseptic precautions, the 

 blood is allowed to coagulate, and the serum is bottled 

 for use. Antitoxin may be obtained in a concentrated 

 form by " salting out " the globulin constituents of an 

 antitoxic serum (p. 167), and a dried product may be 

 prepared by evaporating the serum to dryness in vacuo 

 at 40 C. ( 10 c.c. serum = 1 grm. dry residue). 



The mode of production of the antitoxin by the injection 

 of the toxin has been the subject of various theories. By 



