TOXINS AND ANTITOXINS 



249 



Table VII 



Standardization of Toxin 



Diphtheii?. toxin — strength to be determined. 

 Diphtheria antitoxin contains 300 units per e.c. 

 Temperature of bath — 54° C. 



Lf Dose of Toxin. — It will be observed from an inspection of 

 the above protocol that a floeculent precipitate appeared first in 

 tube 3 to which had been added 0.12 c.c. of antitoxin. The 

 antitoxin contains 300 units per cubic centimeter, therefore 0.12 

 c.c. represents 36 units. Since 3.0 c.c. of toxin brings about the 

 most rapid flocculation of 36 units of antitoxin, one unit of the 

 latter will be flocculated by 0.0833 c.c. of toxin. This amount of 

 toxin constitutes an Lf or flocculating dose. If the Lf dose of 

 toxin is known and the strength of antitoxin is unknown, the 

 latter can be determined by a similar experiment. In practice 

 an experiment similar to the above can be used as a trial titration. 

 In the final titration the difference in the antitoxin content of 

 any two adjacent tubes in the series may be reduced to 0.01 or 

 0.001 c.c, the range being determined by the trial titration. 



Ramon (1922) found that purified antitoxin consisting for the 

 most part of pseudoglobulins is devoid of flocculation power when 

 mixed with toxin. He and also Bayne- Jones confirmed the ob- 



