EDWIN J. BANZHAF 753 



The studies of Moloney and Weld,' Bronfenbrenner and Reichert/ on the toxin- 

 antitoxin flocculation phenomenon indicate that the flocculation is not due to the 

 union of toxin and antitoxin but that it is a specific antibacterial precipitation. The 

 fact remains, however, that even though the flocculation phenomenon may not be due 

 to the union of toxin and antitoxin, these substances are carried down possibly by 

 absorption, with the precipitate caused by the specific bacterial and antibacterial 

 substances. The toxin-antitoxin in the precipitate is insoluble in normal saline solu- 

 tion. Repeated washings do not lessen the active antigenic value of the precipitate 

 (Hartley). 3 



PREPARATION OF ANTITOXINS 



Active immunization for the purpose of obtaining a high antitoxic content in the 

 blood of animals is based on the repeated injections of toxins. The toxins used for the 

 immunization may be modified by physical or chemical means, aging, sunlight, heat, 

 formaldehyde, iodine, or by their specific antitoxins. The toxins are injected either 

 subcutaneously or intramuscularly in any suitable part of the body. During the first 

 stages of immunization the injections of certain toxins may be followed by edema 

 and tenderness at the sites of injections. There may be a rise of temperature, loss of 

 appetite, and general malaise. These conditions may last twenty-four hours or may 

 be prolonged for several days, depending on the amount and source of toxin injected, 

 and upon the sensitivity of the animal to the toxin. 



Diphtheria antitoxin. — In general, horses which show a natural antitoxic im- 

 munity respond promptly to the stimulating effect of the early injections of toxin and 

 are usually not sensitive during the course of immunization. Those which have no 

 natural immunity respond slowly, as evinced by their extreme sensitivity to the early 

 injections of the toxin. Human beings respond similarly, those with traces of anti- 

 toxic immunity responding promptly to toxin-antitoxin injections, and those with no 

 material immunity responding slowly, requiring three to four months before giving a 

 negative Schick test. 



Horses selected for active immunization should be reasonably young, vigorous, 

 and healthy. They should be tested for the absence of glanders and for natural anti- 

 toxic immunity. All horses, of whatever size or breed, are equally responsive to active 

 immunizations. By appearances one cannot judge whether or not a horse will respond 

 and give a high antitoxic content. 



In large establishments, horses are immunized in groups of twenty or more. They are 

 all started with the same amounts of toxin followed by the same increase of amounts (100 

 per cent increase for the first four injections, then the percentage of increase is reduced). Usu- 

 ally as early as the third or fourth injections, marked differences in sensitiveness will be 

 observed in about 20 per cent of the horses. These will show edema, tenderness at the site of 

 injection, and a rise in temperature dropping to normal next day. If the scheduled increased 

 injections are continued as in the non-reactors, these conditions are aggravated and the rise 

 in temperature will be prolonged. Scheduled injections are then omitted until the temper- 



' Moloney, P. J., and Weld, C. B.: ibid., 28, 655. 1925. 



* Bronfenbrenner, J. J., and Reichert, P.: /. Expcr. Med., 44, 553. 1926. 



3 Hartley, P. : loc. cit. 



