The flocculation of tetanus toxin and toxoid. I

Summary

• 1. The flocculation of tetanus toxins and toxoids produced in a modified Tarozzi broth was made the subject of an exhaustive study.

• 2. At least three flocculation zones were found.

• 3. The lowest flocculation value always proved to agree with the true point of equivalence of the antitoxin-binding (A.B.V.).

• 4. When mixtures of toxin and antitoxin were injected into mice, only about half the total quantity of antitoxin that can be bound (as appears from A.B.V. or Lf) appeared to be required for the neutralization of the toxic effect. The quantity of toxin thus found was indicated as M.T.V. So this M.T.V. is approximately 1/2 × A.B.V. or Lf.

• 5. During the incubation of tetanus cultures all flocculation values (3 or 4) increase steadily.

• 6. The d.l.m. also increases regularly, but much more quickly, hence the ratio m.l.d./Lf increases very considerably during incubation.

• 7. At the same time the ratio M.T.V./Lf remains constant, i.e. about 1/2.

• 8. The possible theoretical explanation of the different problems was discussed.